List_of_The_Big_Bang_Theory_episodes

After an unsuccessful visit to the high-IQ sperm bank, Leonard (Johnny Galecki) and Sheldon (Jim Parsons) return home to find out Penny (Kaley Cuoco), a new neighbour, has moved in across the hall. Leonard immediately becomes interested in her, while Sheldon feels his friend is chasing a dream he'll never catch. Later, Leonard invites Penny to his and Sheldon's apartment, where she gets to meet their friends Howard Wolowitz (Simon Helberg), a wannabe ladies man, and Rajesh Koothrappali (Kunal Nayyar), who is so shy he cannot speak to women.

When Sheldon and Leonard go over to Penny's apartment to drop off a package that came for her, Sheldon is deeply disturbed when he sees how messy and disorganized her apartment appears. Later that night, while Penny sleeps, Sheldon sneaks into her apartment to clean and organize it; Leonard catches him and reluctantly helps him clean. The next morning, Penny realizes the changes made in her apartment and becomes very upset about it. Sheldon tries apologizing to Penny but fails after remarking that Leonard is a "thorough and gentle lover". Later, Penny encounters Raj in the hallway and chats with him, finally realizing that the guys were just trying to help her. Leonard then apologizes, prompting Penny to hug him and forgive him.

When Leonard sees Penny kissing a guy in front of her apartment door, he is devastated thinking she has "rejected" him. The guys convince him to ask someone out at work, so he asks out fellow scientist Leslie Winkle (Sara Gilbert), who brutally turns him down. As Leonard slips deeper into his depression, which involves thinking about buying a cat, Sheldon points out that he was not actually rejected, as he had not asked Penny out. Leonard agrees and promptly asks Penny out to dinner, but she mistakes his invite as an invitation to hang with all the guys. Despite being aware of this, Leonard keeps the date and makes up excuses as to why the guys were absent.

On the date, Penny mentions the man Leonard saw was not her boyfriend, but that she has a habit of having weekend-long casual sex encounters to get over relationships. Excited, Leonard begins to become more confident but, after accidentally hurting himself, the date becomes a disaster and Penny takes him home. Leonard does not get the courage to reveal his true feelings to Penny, even though she suspected what he was up to.

Sheldon is fired from his job as a physicist at the university when he insults his new boss Dr. Eric Gablehauser (Mark Harelik). His change of circumstance sends him into a downward spiral of depression which Leonard tries to cure by sending for Sheldon's mom, Mary Cooper (Laurie Metcalf). When she arrives for a visit, the boys realize she is completely the opposite from what they expected; she is down-to-earth, sweet, and a devout Christian. After waiting it out, Mary finally forces Sheldon to apologize, and he is given his job back after she flirts with Dr. Gablehauser. As Mary is a widow, Sheldon asks if Dr. Gablehauser will be his new daddy and his mother replies, "We'll see..."

While eating at the Cheesecake Factory where Penny works, the guys run into Leslie Winkle, a fellow scientist who works with Leonard (and previously turned him down for a date saying she had no attraction to him). She suggests that Leonard play in her string quartet as they are in need of a new cellist. However, what she really wants is to get personal with Leonard (especially after hearing him play the cello).

When Sheldon comes home and finds a necktie on Leonard's door, he runs to Penny’s apartment to ask her what the necktie means. Penny tells him and seems slightly disappointed, though she does congratulate Leonard later on. Leonard tries to figure out what her words meant, but eventually gives up, deciding he should choose a real relationship (Leslie) over an imaginary one (Penny). However when he arrives in the lab, Leslie makes it clear she used him just to satisfy her sex drive, saying she's 'good till New Year's'. Leonard later tells Penny, who walks away with a smile on her face; she seems to be quite happy to hear this news.

The guys are invited to Penny's Halloween party, first turning it down as they don't dance but changing their mind when costumes are mentioned. At the party, the guys have problems socializing; for example, Sheldon is unable to explain his costume as the Doppler effect, and Raj cannot speak to women. Later, Penny's ex-boyfriend Kurt (Brian Wade) shows up and confronts Leonard, causing him to leave. Penny goes to check on him and apologizes; both drunk and upset, she kisses Leonard before she goes back to the party. Meanwhile, Howard cannot find Raj, who ends up going home and has sex with a girl he had met at the party, who found him to be a "good listener".

Penny's promiscuous 'friend' Christy (Brooke D'Orsay) from Nebraska is in town, and ends up being seduced by Howard. The pair take over her apartment causing her to sleep on Leonard and Sheldon's couch for the night. With Howard gone, Penny takes his place on their Halo team, causing Sheldon much distress as she is naturally good at it. Christy moves in with Howard (and his mother) taking up all his time. Sheldon is distraught over the odd number in the group believing they can no longer function. He's even more distraught when he relents and lets Penny join in on Halo night, but she declines the offer to go dancing with her friend instead. Believing that they are falling apart as a group, the guys go to speak to Howard. When they arrive they hear Christy and Howard's mother arguing loudly, causing Christy to leave. Howard, once again single, says 'So, Halo night?' and the group is restored.

Raj introduces his parents, Dr. and Mrs. V.M. Koothrappali (Brian George and Alice Amter), via web cam to his friends. However, Raj immediately becomes overwhelmed after his parents try to arrange a date with Lalita Gupta (Sarayu Rao), a childhood friend, as he cannot talk to women. Meanwhile, Penny takes up bar tending for some extra money. As she practices mixing drinks with the guys, they discover that after a few drinks Raj can actually talk to women. They decide the date should be at Penny's restaurant, so she and the guys can keep an eye on Raj's behavior while drinking.

However, on his date Raj becomes very obnoxious, and Lalita ends up leaving with Sheldon, who compliments her by comparing her to Princess Panchali, an Indian princess in a fairy tale. Back from the restaurant, Raj tries to explain to his parents what happened. Even though he is already upset, things become worse when his parents find out he was drinking.

Cleaning up after an internet experiment, Leonard discovers a letter in the trash can. He and Sheldon had been invited to present some research they had done together at a physics conference. However Sheldon does not believe in such things and says if he won't go, no one can. Leonard defies him and says he will go and present the findings on his own. This causes a rift between the two which Penny tries to mend but accidentally makes worse. At the conference Sheldon appears and not only tries to "blow up" Leonard's head with his mind a la the movie Scanners, but has a physical altercation with Leonard. In the end, the fight is captured by Howard and put on YouTube.

Penny was given a part in Rent, though after hearing her sing extremely off-key Leonard lies to avoid seeing her performance so he won't hurt her feelings. Sheldon becomes worried that Leonard's lie was not good enough, so he creates an intricate lie about his non-existent drug addicted cousin "Leopold Houston", who was in need of an intervention (and thus why they could not see the play). Sheldon becomes so obsessed with the credibility of his lie, that he has Toby Loobenfeld (DJ Qualls), a research assistant who double majored in Physics and Theatre, impersonate cousin "Leo" to convince Penny that the lie is true. In the end, Leonard still has to see the videotape of Penny's performance.

Penny returns from visiting family in Nebraska, and as she picks up her mail from Leonard, she mentions most of her relatives got sick. Sheldon freaks out as, according to Leonard, he is a "germaphobe". Sure enough, Sheldon becomes sick and instantly becomes the biggest pain possible. As it's evident this has happened before, Leonard and the guys hide from him at a Planet of the Apes marathon, leaving Penny unwillingly to take care of Sheldon. However, Leonard accidentally breaks his glasses and must re-enter the apartment, where Penny catches him and sticks him with Sheldon. In the end, both Leonard and Sheldon are sitting sick and injured on the couch.

Sheldon is overcome with envy when he meets 15-year-old child prodigy Dennis Kim (Austin Lee). Losing faith in his own research, Sheldon annoys his circle of friends by visiting them and criticizing their work. Deciding his work in physics is useless, he decides to aim for the Nobel Peace Prize by solving the Middle East conflicts: he proposes the creation of an exact replica of Jerusalem ("Nuevo Jerusalem") for the Jewish people in the Mexican desert.

The guys, getting tired of Sheldon's behavior, decide to take Dennis out of the picture by getting him distracted with girls of his age. At his welcome party, their plan works out and Dennis leaves with a blonde 15 year old for the shopping mall. Excited, Sheldon declares his intention to resume his research, and the guys are left perplexed at how easily Dennis was able to get a girl.

The guys decide to compete in a physics bowl after finding out that strong competitors have dropped out. However, they find Sheldon's showboating too much and kick him off the team. Upset, Sheldon vows to form his own team and compete against them. The guys, in need of a 4th member, ask Leslie Winkle to join them; she rejects the offer at first, but reconsiders after finding out they are going against Sheldon, who has made fun of her research many times.

At the bowl, the guys team is called PMS (Perpetual Motion Squad, a pun on Premenstrual syndrome); Sheldon's team is named AA (Army ants, a pun on Alcoholics Anonymous), and is composed of himself, the 3rd floor janitor, the lunch lady, and her son (or butcher). PMS wins the competition when Sheldon, himself unable to answer the last question, won't accept the janitor's answer, which turns out to be correct. The janitor explains that despite working in America as a janitor, he was a physicist in former Soviet Union.

Online, Leonard buys a replica time machine from the 1960 film, The Time Machine, believing it to be a miniature, though it turns out to be full-sized. As the boys move it into the apartment, they accidentally make Penny late for work causing her to lash out at Leonard for his nerdy ways. Upset, Leonard decides to get rid of all his collectibles, while his friends try to convince him not to. In the end, Sheldon confronts Penny about her own love of childish things (Hello Kitty, Beanie Babies, My Little Pony, etc.) and she apologizes to Leonard. However, she has a new boyfriend named Mike, and once Leonard finds this out, he reverts to his old ways.

The guys see an attractive woman in Sheldon's office, and they become even more surprised when Sheldon introduces her as his fraternal twin sister, Missy (Courtney Henggeler). After meeting her, Raj decides to take part in a drug trial to cure his inability to talk to women, and Leonard insists she stay with them at the apartment. Naturally, the boys instantly try to hit on her, causing Penny to come to her rescue.

Later, Leonard convinces Sheldon to be protective of Missy, so he can have a chance at her over Howard and Raj; however, much to Leonard's chagrin, Sheldon deems all three unsuitable to be with his sister. Upon learning about Sheldon's plan to find a suitable mate for her, Missy confronts her brother, and Sheldon agrees to let Missy date whoever she wants. Leonard wins first chance to ask Missy out, but she turns him down; Howard tries next, but she turns him down as well; finally, Raj goes to talk to Missy, but at that precise moment the drug wears off and he is unable to speak to her, forcing him to leave defeated.

When the boys dine at Penny's restaurant, she learns Leonard has never had a birthday party, as his parents didn't believe in celebrating anything but achievements. She decides to throw him a surprise party, and blackmails Sheldon to join her. However, when the day of the party arrives, Penny finds Sheldon did not buy a birthday gift, so she has to drive him to a computer store to pick up a present.

Meanwhile, Howard is in charge of keeping Leonard out of his apartment until the party. Howard pretends to eat a peanut bar, to which he is allergic, so Leonard can drive him to the emergency room. However, due to Sheldon's absent-mindedness in the computer store, Howard has to keep Leonard distracted even longer, and he is forced to actually eat the peanut bar, causing him to swell up in a severe allergic reaction.

After being at the hospital for several hours, Howard and Leonard arrive back at the apartment to find the party has ended.

Penny breaks up with her boyfriend after he posted details about their sex life on his blog. Meanwhile, Sheldon asks Howard to teach him Mandarin as he's convinced the Chinese restaurant is selling "Tangerine chicken" yet is really using oranges, a cheaper citrus.

As Penny laments her choices in men, Leonard awkwardly asks her on a real date, and she accepts. A few days pass and both Leonard and Penny are worried that this date could ruin their friendship. They both seek Sheldon's advice, who uses the "Schrödinger's cat" experiment to explain that at this time, the date has both "good" and "bad" possible outcomes, and the only way to find out is to go on the date and find which outcome it is. When Leonard arrives to pick Penny up, he passionately kisses her, and they leave for dinner.

In the end, Leonard and Penny are seen going to the Chinese restaurant, but they leave before entering as they realize Sheldon, in fractured Mandarin, is fighting with the owner (James Hong).

Penny and Leonard return from their first date while Howard and Rajesh spy on them using a webcam on the corridor. Penny tells Leonard that they should "slow things down", and the guys try to convince Leonard that the date didn't go well. On the other hand, Penny reveals to Sheldon that she lied to Leonard about completing community college, as she is afraid that she isn't smart enough for him. Subsequently, Penny asks Sheldon to keep this as a secret, but this request becomes to hard for him that he makes the drastic decision to move out of his and Leonard's apartment.

After staying briefly with Raj, and then Howard, a drugged Sheldon is brought back to Leonard's apartment, where he admits that Penny didn't complete community college. The next day, in an attempt to help her, Leonard offers Penny some pamphlets regarding a local community college, but accidentally mentions that he is fine with dating a girl "who isn't smart". Penny promptly slams the door in his face as Leonard realizes his mistake.

After the guys return from a Renaissance fair and see Penny with her new boyfriend, Eric (Travis Schuldt), Leonard decides to once again pursue a relationship with fellow physicist Leslie Winkle (Sara Gilbert). Thinking that she needs to "slow things down", Leslie agrees to date Leonard, repeatedly assuming the dominant role before conceding that Leonard should assume the "male role". With this new attitude, Leslie goes as far as evaluating Leonard's genetic defects, and talking about procreating children with him.

Sheldon explains to Penny that he feels uncomfortable with Leonard dating his arch enemy, who is a "sloppy, arrogant, sub-par scientist". After Penny's advice, Sheldon formally approves the relationship between Leonard and Leslie. However, almost immediately, Leslie and Sheldon start an argument about the validity of loop quantum gravity, which Leslie supports, and string theory, which Sheldon supports. Leslie expects Leonard to back up her beliefs, but when Leonard prefers string theory, Leslie decides to dump him.

Sheldon becomes distracted from playing Age of Conan by Penny who has been accidentally left out of her apartment. Along with this event, Penny is frustrated by her failures in life such as not progressing in her acting career, and not having sex for six months. As Sheldon invites Penny into his apartment to wait for the locksmith to open her door, she becomes curious about the game Sheldon is playing, and quickly becomes addicted.

In the following days, Penny experiences video game addiction, calls Sheldon at all times for help, and stops going to work to play the game nonstop. After talking with Leslie Winkle, Sheldon realizes that Penny needs to have sex to relieve her stress and regain her regular life. Sheldon then attempts to set Penny up with an online dating service, but fails miserably. In the end, Penny overcomes her addiction when she realizes she accepted to have a virtual date with Howard. Horrified, she promptly stops playing.

Raj is included in People magazine's "30 visionaries under 30 years to watch" list for his discovery of the trans-Neptunian object 2008 NQ₁₇, sparking jealousy from his friends. Despite Leonard's comments that they need to be supportive, fame soon goes to Raj's head: he receives star treatment from Dr. Gablehauser (Mark Harelik), gets an assistant, and even invites Penny to People's reception.

After the party, a very intoxicated Raj returns home with Penny, and via webcam introduces her to his parents as his girlfriend; the night ends with Penny leaving and denying being Raj's girlfriend, and with him feeling sick from drinking too much. The following morning, a sober and shy Raj tries to apologize to Penny for his behavior. Although Raj tried to leave a written note, Penny ultimately forced him to utter a barely audible "Sorry", at which point she forgave him.

The episode includes a cameo appearance from Charlie Sheen; at Penny's restaurant Raj tells to a patron that he is going to appear in People magazine, but the patron, Sheen, turns around and says "Yeah? Call me when you're on the cover."

Leonard is working nights on an experiment, resulting in his inability to drive Sheldon to the university. As a result, Sheldon must find another way to get to work. He asks Penny, Howard and Raj for assistance, but they all eject him from their respective vehicles for being annoying. The friends finally stage an "intervention" and tell Sheldon to get a driver's license and learn to drive.

After an eventful trip to the DMV, resulting in Sheldon getting his learner's permit, the group sets up a computer simulation for him in the living room. The ensuing practice shows that Sheldon is a horrible driver, but instead of admitting defeat, he simply concludes that he is too highly evolved to drive a car. In the end, Sheldon decided to live in his office at the university, so he didn't have to commute. However, Leonard revels that he actually finished his experiment a week ago and is just enjoying the apartment without Sheldon.

After a lecture by Leonard and Sheldon, a graduate student named Ramona Nowitzki (Riki Lindhome) becomes obsessed with Sheldon, and insinuates herself into his life as a girlfriend/assistant. Ramona proves to be a helpful influence on Sheldon's work, but he becomes tired of her as she prohibits him recreational activities, and forces him to solely concentrate on his research.

Sheldon finally realizes that he is in "some sort of relationship" with Ramona, and seeks help from Penny and Leonard to get rid of her, without success. Things come to a conclusion when Sheldon reaches a breakthrough in his scientific research, and Ramona suggests they share credit for his discovery. Naturally, Sheldon refuses to share credit, and subsequently kicks Ramona out. In the end, after reading a draft paper of the new theorem, another student approaches Sheldon in the same way Ramona did the first time.

When Penny's cable gets cut, she starts coming over to the guys' apartment to watch America's Next Top Model. However, Sheldon bans her from the apartment for a series of petty infractions, such as touching his food, sitting in his spot, and sending him "email humor". After a series of escalating pranks, including Sheldon cutting off Penny's access to WiFi and Penny wrecking Sheldon's "laundry night", Sheldon goes to the extreme of hanging her laundry from a telephone wire outside his apartment. Leonard decides to help Penny end the war, and gives her Sheldon's "Kryptonite": his mother's phone number. Subsequently, Sheldon's mother calls him and forces him to apologize to Penny.

Meanwhile, Howard and Raj try to find the location of the Next Top Model house in Los Angeles. They use all of the technology at their disposal, including a military spy plane and NASA satellites to finally pinpoint it. In the end, they arrive at the house, and posing as cable guys work their way in. The episode ends with cameos of Analeigh Tipton and Samantha Potter of America's Next Top Model, Cycle 11.

A smitten Howard thinks he's found his soul mate, until the woman, Dr. Stephanie Barnett (Sara Rue), meets Leonard. Howard invites Stephanie to drive the Mars rover at a secret facility, but the plan fails when the rover winds up stuck in a Martian ditch. Subsequently, to hide evidence of what he did, Howard destroys all the security tapes and hard drives relating to the mission.

Afterwards, Leonard has a hard time deciding how to tell Howard that he has started dating Stephanie. Leonard decides to go to Howard's house to tell him personally, but while there, Stephanie calls Howard and gives him the news. Howard becomes very upset with Leonard, but this only lasts until Stephanie sets up Howard with another friend, and invites him on a double-date. In the end, Howard hears the news on TV that the rover found water on Mars in the bottom of the ditch, but as so much data was "inexplicably" lost no one will know who was responsible for the amazing discovery.

Sheldon considers Dr. Stephanie Barnett (Sara Rue) the only "tolerable" girlfriend that Leonard has had. As a result, Sheldon tries helping Leonard in his relationship with Stephanie, as otherwise he thinks Leonard will ruin it. However, Leonard doesn't want Sheldon's help as he quickly becomes annoying, even joining the couple when they have a romantic dinner, and when they go to the movies.

After believing that Leonard is losing Stephanie, Sheldon attempts to prove Leonard's physical superiority to Stephanie by having him open a jar of white asparagus. However, Leonard shatters the jar by accident and has to get stitches. Following the trip to the hospital, Leonard finds Sheldon hacked his Facebook account, and changed his status to "In a relationship". Despite Leonard's complaints that this makes him look desperate, it is revealed that, in response, Stephanie updated her status too. In the end, it appears that Dr. Sheldon Cooper helped the couple after all.

For all practical purposes, Leonard's current girlfriend, Dr. Stephanie Barnett (Sara Rue), has moved into Leonard and Sheldon's apartment, although Leonard doesn't acknowledge this. Meanwhile, Stephanie gives a physical examination to Sheldon who complains about a ringing in his ear. After Penny shows up scantily clad in the guys' apartment, it turns out that neither Leonard nor Sheldon ever told Stephanie about Penny. The morning does not go well following that; Penny proves to Leonard that Stephanie is living with him, and Stephanie buys Leonard new clothes that he ends ups hating.

Realizing that his relationship with Stephanie is moving too fast for him, Leonard tries to tell Stephanie to move out, but every time he tries they instead end up having sex. Meanwhile, Sheldon sneaks into the hospital to test himself multiple times, as the ringing hasn't stopped. By the time Leonard gets back to the apartment, Stephanie has diagnosed Sheldon with a fake larynx inflammation, and instructs him not to speak at all. Although Leonard and Stephanie are not seen breaking up, evidence suggest they ended their relationship, as Stephanie doesn't appear in the following episodes.

Leonard meets visiting researcher Dr. David Underhill (Michael Trucco), who is an experimental physicist like he is. Although initially Leonard shows envy towards David because he is handsome, charming, cool, and a more successful physicist than he is, almost immediately he changes his mind and happily jumps at David's offer to help him in his research. However, Leonard's joy of hanging out with David is hampered by jealousy when the latter meets Penny, and the two start dating. However, soon after, Penny reveals that she broke up with David as he is actually newly married.

Meanwhile, Sheldon, having always viewed Christmas as the pagan ritual of Saturnalia, is taken by surprise when Penny brings him a wrapped gift. Sheldon now feels obliged to buy her a gift of equal value, despite not knowing the contents of the her gift. In the end, Penny's gift turns out to be a napkin autographed by Leonard Nimoy (the original Mr. Spock in Star Trek: The Original Series, and one of Sheldon's idols). Shocked and delighted at the same time, Sheldon gives Penny all the presents he bought, and even manages to give her a hug.

When Penny's harsh comments about Howard's love life sends him into depression, his friends lose their most important team-mate in an upcoming fighting robot competition. Subsequently, when Sheldon accepts a challenge for a one on one fight, pitting their robot, M.O.N.T.E. (Mobile Omnidirectional Neutralization and Termination Eradicator), against "the Kripke Krippler" from their co-worker, Barry Kripke (John Ross Bowie), Leonard tries to get Howard back on their team by sending Penny to apologize to him.

Penny goes to Howard's house to apologize, and ends up hearing his entire dating history. After Penny's comforting words, Howard tries to kiss her, but she reacts and punches him in the face. Meanwhile, M.O.N.T.E. is destroyed beyond repair. In the end, save for the broken nose, Howard is back to normal.

Sheldon realizes that Barry Kripke (John Ross Bowie) is in control of an open science grid computer, so he plans to befriend him to get access to the computer. Socially inept, Sheldon has trouble understanding how to make a new friend, and his current friends aren't of much help in this respect.

After a trip to the bookstore, Sheldon uses a children's book to help him design a flowchart to get new friends. This "scientific" procedure pays off, and Sheldon goes rock-climbing with Kripke. Afterwards, they are back at the apartment, where Sheldon decides to cut off Raj as a friend to make room for Kripke. However, when Kripke reveals that he does not control who uses the grid computer, Sheldon promptly dismisses Kripke as his friend and restores Raj's place in the line-up.

Penny is experiencing financial difficulties which may result in her finding a new place to live. After discussing this with Sheldon, Sheldon does the logical thing and lets her borrow enough money to cover her needs. Later, after Leonard learns about Penny's problems, he tries to help her cut expenses, and in the process also learns that her ex-boyfriend Kurt (Brian Wade) owes her a big sum of money.

Without telling Penny, Leonard and the guys go to Kurt's place to collect the money, but they are unsuccessful. Later, Penny is able to pay Sheldon back, and she reveals that Kurt actually paid her in turn. However, much to Leonard's disappointment, Kurt never told Penny about Leonard's visit, and instead took the opportunity to get back together with her.

Leonard suddenly becomes worried when he learns he will receive the visit of his mother, Dr. Beverly Hofstadter (Christine Baranski), who is an accomplished psychiatrist and neuroscientist. Upon arriving to the building, Beverly meets Penny, and by the time they reach Leonard's apartment, Penny is in tears after being psychoanalysed, revealing her childhood issues. Sheldon, on the other hand, instantly develops a comfortable relationship with Leonard's mother, who turns out to be as strict and logical as himself.

Howard and Raj also meet Beverly, but after learning that Howard still lives with his mother and that Raj can't speak to women, she is quick to declare that they are living a "homosexual marriage". Later, Leonard goes to talk to Penny, and they both seek comfort in each other, discussing their respective childhood issues with their parents. As they become drunk, Penny and Leonard are about to have sex, but Leonard ruins the moment by using psychology and noting that "he is having sex with his mom" and that "she is having sex with her dad". Following this, Penny throws Leonard out of the apartment.

A paintball game leads to a romance for Howard and Leonard's former girlfriend, Leslie Winkle (Sarah Gilbert). At the apartment, Penny accidentally shoots the paintball gun at Sheldon's couch cushion, and she and Leonard have a hard time getting it cleaned. Naturally, Sheldon freaks out when he finds out.

Meanwhile, Leslie and Howard start sleeping together, and she is able to secure funds for his work, and even invites him to a trip to the CERN Large Hadron Collider project in Geneva. However, this turns out to be just Leslie's way to control Howard. Although initially reluctant to be in this sort of relationship, Howard later happily accepts his role as a "sex toy/arm candy". In the end, Sheldon is still dissatisfied with the dry-cleaned cushion, and he shoots Penny in the next paintball game.

The guys take a train trip to a conference in San Francisco, where the guest speaker is 2006 Nobel Prize laureate Dr. George Smoot. However, the trip suddenly becomes more exciting when the guys realize Summer Glau (guest starring as herself) of Terminator: The Sarah Connor Chronicles is on board.

Leaving his shyness behind while drinking beer, Raj is the first to approach Summer. However, when the beer turns out to be non-alcoholic, Raj reverts to his usual timid self. Howard then takes over, but creeps Summer out with his wild dreams. Leonard eventually gets his chance, but Summer gets off the train before he can introduce himself. Meanwhile, Sheldon realizes he forgot his USB flash drive with a paper he wants to show to Smoot, and he needs Penny to find it in his room and email the paper to him. In the end, Dr. Smoot (guest starring as himself) is not impressed with Sheldon's proposal of research, asking him "With all due respect, Dr. Cooper, are you on crack?"

Penny develops a home-made hair barrette, called the "Penny blossom", which she expects to turn into a profitable home business. Sheldon soon points out the flaws in her production process, and helps her setting a better assembly line. Leonard, Howard, and Raj also contribute their own ideas for efficiency, production and marketing.

Leonard designs the sales website, and right away they get an order for 1 000 blossoms from the "East Rutherford, New Jersey Gay-Lesbian-Bisexual-Transgender Alliance". Despite their initial happiness, they realize Leonard included a one-day rush shipping option in the website, so the quintet has to work all night to fulfill the order. However, the next morning, they discover that the same group doubled their order, leading everyone to quit in exhaustion.

The former tenants of the apartment above Leonard and Sheldon's move out, and are replaced by an attractive blonde woman named Alicia (Valerie Azlynn). Alicia, like Penny, is an aspiring actress, but a more successful one, landing a role in the TV series CSI. Naturally, the guys become fascinated with Alicia, and she takes advantage of this by having them do stuff for her.

On the other hand, Penny becomes jealous, thinking that Alicia is supplanting her in the boys' attention. Subsequently, Penny tries to gain her friends back by bribing them with Chinese food, offering to watch Battlestar Galactica, and even memorizing a quantum physics joke. Alicia points out that Penny uses the same routine on the guys that she does, and after that, the two have a catfight in the lobby, resulting in a black eye for Penny and ecstasy for Howard. In the end, Penny has reclaimed her men, while Alicia is heard having sex with one of the producers of CSI.

Penny needs a present for her nephew's birthday, so she accompanies the guys to the comic book store. There, she meets the owner, Stuart (Kevin Sussman), who manages to ask her out on a date. Feeling jealous about the situation, Leonard decides to go out with Howard and Raj to pick up women at a bar.

Stuart's date with Penny goes well, but they are interrupted by Sheldon who starts an argument about Batman's successor should Batman be killed. Sheldon "wins" the discussion when Stuart announces he is tired and needs to leave, whereupon they discover that Penny has fallen asleep from boredom. Meanwhile, at the bar, Raj is the only one who succeeds in getting a girl.

Leslie Winkle (Sarah Gilbert) ends her "friends with benefits" relationship with Howard, and he becomes depressed. Leonard and Raj decide to take him on a trip to Las Vegas in order to cheer him up. Meanwhile, Sheldon, who has declined to go to Las Vegas, is ready to spend the weekend alone.

While in Vegas, a prostitute named Mikaela (Jodi Lyn O'Keefe) approaches Raj, and eventually he and Leonard decide to hire her for Howard. Howard soon realizes she is a prostitute, but nevertheless he thanks Leonard and Raj for setting up this "date". Meanwhile, Sheldon, having forgotten his apartment key, is forced to spend the night at Penny's apartment. In the end, Sheldon thinks he has a better understanding of the term "friends with benefits".

Howard celebrates the launch of his zero-gravity human-waste disposal system, a "space toilet" to be used in the International Space Station, by buying all of his friends new comic books. While at the comic book store, Stuart (Kevin Sussman) tells Leonard that he is having a second date with Penny and asks for advice. Leonard deliberately avoids Stuart's request, and ultimately gives him bad advice.

The next day, Leonard feels guilty and goes to apologize to Stuart. Stuart reveals the date when fine, until he and Penny started kissing and Penny accidentally blurted out Leonard's name in place of Stuart's. Meanwhile, Howard discovers that he made a mistake that will cause the toilet to fail after a few flushes, and he seeks his friends help to fix it. In the end, it appears the toilet failed anyway, as the astronauts go on an unscheduled "spacewalk".

Sheldon wins a National Science Foundation grant to go on a three-month expedition to the North Magnetic Pole to detect magnetic monopoles and prove the validity of string theory. After some hesitation, he decides to go, and wants Leonard, Howard and Raj to join him; although initially reluctant, as it implies spending three months locked in a cabin with Sheldon, they agree.

To prepare for the cold weather, Sheldon asks Penny to give them access to the freezer at the Cheesecake Factory. When Penny learns that Leonard is also going, she is seemingly upset. Later, she gives him a blanket as a gift, and saying she'll miss him, she also gives him an unusually long hug. On the morning of the guys' departure, Leonard asks Penny about the long hug, but she doesn't reveal her true feelings for him. Only after they leave, Penny whispers to herself "It means I wish you weren't going".

After their return home from their three-month expedition in the North Pole, Sheldon finds out from Howard and Raj that the guys had tampered with his experiment because Sheldon was absolutely unbearable when he wasn't getting the results he wanted (plans to kill him were even brought up and discussed). They tell him about their use of an electric can opener to give Sheldon positive results, thereby causing Sheldon to believe he has made a Nobel Prize-winning discovery. Unfortunately, Sheldon had immediately emailed everyone at Caltech about his discovery before Howard and Raj could tell him what had happened. Sheldon is so disgraced that he resigns and moves back in with his mother (played by Laurie Metcalf), who lives in east Texas. Mrs. Cooper calls Leonard and tells them that they should come talk to Sheldon. Upon the guys' arrival, Sheldon is intent on staying in Texas. However, he shortly has a disagreement with his mother about creationism versus evolution and decides to return to California. Meanwhile, Penny has been harboring feelings for Leonard, which are released almost as soon as he comes home. Leonard's "moments" with her are constantly interrupted, and he "cannot catch a break." They finally sleep together at the end of the episode (Leonard finally "catches his break") and Leonard asks why it's always weird after friends sleep together and why they have to label it as such - "it just is what it is." Penny interrupts him saying "it's weird" and he replies "Totally."

Leonard and Penny struggle to recover from an awkward first hookup and try to figure how to overcome their current problem. A romantic evening between the pair soon turns to a night filled with drunken sickness. The next day Penny talks to Sheldon regarding her current problem with Leonard and Sheldon points out that if things don't work out, they can always return back to being friends. After Sheldon tells Leonard that he spoke to Penny about their problems, Leonard goes to Penny's apartment, there Penny tells Leonard that being friends was much simpler and that it will take the pressure off, something that Leonard agrees to. They decide to go back to being friends, however it's clear that neither wants that and soon give in to their attraction. Meanwhile, Sheldon and Howard stake their most valuable comic books (Sheldon's Flash of Two Worlds against Howard's Fantastic Four #48) on a bet to determine the species of a cricket. Sheldon hears the chirps and says it is a snowy tree cricket and Howard insists it is a common field cricket. Along with

© 2006 diyfurnace.com