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Season 2

18 :02x01 - The Bad Fish Paradigm

Leonard and Penny return from their date, but it ends in an odd matter when Penny wants to take things slower. While Leonard is living his normal everyday life, Penny is now worrying if she is smart enough for Leonard, as she has none of the same interests as him, so she seeks advice from Sheldon and even tells him a secret. However, when it turns out Sheldon can’t keep her secret, the relationship between Leonard and Penny may be broken forever.
Co-Guest Stars: Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski

19 :02x02 - The Codpiece Topology

After Leonard sees Penny with a new guy, he decides it’s time to move on with his life. When Leslie Winkle enters the lab, she invites Leonard to get a relationship. However, Sheldon hates Leslie and Penny wants them to break up, so Penny receives advice from Sheldon, but with no good results. Meanwhile, the relationship hits a bump when it turns out Leonard rather supports Sheldon’s science theories than Leslie’s.
Guest Stars: Travis Schuldt as Eric
Director: Mark Cendrowski
Story: Chuck Lorre | Teleplay: Lee Aronsohn, Bill Prady

20 :02x03 - The Barbarian Sublimation

When Penny becomes depressed due to the thoughts that she fails everything in life, the guys try everything to make her better, but with no results. However, when Penny sees Sheldon’s game, “Age of Conan”, she becomes addicted playing it, and winds up a slob. Meanwhile, the evil sparks between Sheldon and Leslie have still not disappeared.
Guest Stars: Mark Harelik as Dr. Gablehauser (Dr. Eric Gablehauser) |
Co-Guest Stars: Tyler J. Olson as Blaine | Mark Hames as Tom
Director: Mark Cendrowski

21 :02x04 - The Griffin Equivalency

When Koothrappali discovers a new planet, he is honored the ”30 under 30” award from People Magazine, and the guys try to show their spirit by inviting him to dinner, but there is one person who just can’t show his support; Sheldon, who believes receiving an award for something that the recipient didn’t actually create, is fake. The guys try to convince him into thinking otherwise, but when Koothrappali’s self-esteem builds up to the max, he becomes so obnoxious that they all try to avoid him. Meanwhile, Koothrappali invites Penny to go the People Magazine party, but the only way he can talk to Penny is while being drunk, which puts a halt to their friendship.
Special Guest Stars: Charlie Sheen as Himself (Special Appearance by) |
Guest Stars: Mark Harelik as Dr. Gablehauser (Dr. Eric Gablehauser) | Brian George (1) as Dr. Koothrappali | Alice Amter as Mrs. Koothrappali
Director: Mark Cendrowski

22 :02x05 - The Euclid Alternative

When Leonard does experiments where he needs to use a laser only available during the night, he is unable to drive Sheldon to and from work in the morning. Sheldon, who can’t drive, seeks help from Penny, Howard and Koothrappali, but they all get so angry they refuse to drive him. However, the only way for them to get Sheldon off their back is to get him driving a car, which he’s terrible at, leaving the guys and Penny between a rock and a hard place.
Guest Stars: Octavia Spencer as Octavia |
Co-Guest Stars: Elena Campbell-Martinez as Maria | Livia Trevino as Lourdes
Director: Mark Cendrowski

23 :02x06 - The Cooper-Nowitzki Theorem

After speaking at a student seminar, Sheldon quickly finds himself in an unusual situation; a girl approaches him interested in helping him with his research. Not needing the help, Sheldon instead gets her to take care of all his daily work for him so he can focus entirely on his work. However, when she gets too pushy, going as far as washing his feet while he works, Sheldon seeks advice from Penny in order to get her off his back, but it’s harder than they thought. Meanwhile, the guys are baffled that someone can survive a full day with Sheldon as she does, and they begin to miss Sheldon during Halo, paintball and other such activities.
Guest Stars: Riki Lindhome as Ramona (Ramona Nowitzki) | Emily Happe as Kathy (Kathy O'Brien)
Director: Mark Cendrowski

24 :02x07 - The Panty Piñata Polarization

Officially becoming a member of their group, according to Sheldon, Penny has huge problems fitting in with the house rules. When Penny gets “3 strikes”, she is banished and can’t even talk to Sheldon anymore, putting Leonard in a difficult situation where he must choose which side of the argument he should stay on. Meanwhile, Penny declares a war between Sheldon and her, where the weak sides of them both are exposed; Penny’s lingerie is put out on a telephone wire, while Sheldon’s “laundry day” is ruined when all the machines are taken, and there seems to be no end of this war.
Co-Guest Stars: Analeigh Tipton as Analeigh | Samantha Potter as model
Director: Mark Cendrowski

25 :02x08 - The Lizard-Spock Expansion

Wolowitz has once again used his “dating skills” to make a mess when he invites a girl, Stephanie, to drive the Mars Rover, only to have it stuck in a ditch. He now needs help from the other guys, but he also wants someone to take care of Stephanie, whom Leonard drives home. However, when Leonard and Stephanie kiss in the car and start a relationship, Wolowitz becomes so angry at him he starts ignoring them both completely. Meanwhile, Penny is so happy that Leonard is in a relationship, but he’s not sure if it pushes Penny away from him or not.
Guest Stars: Sara Rue as Stephanie (Dr. Stephanie Barnett) | Carol Ann Susi as Mrs. Wolowitz |
Co-Guest Stars: Jennifer Hale as News Announcer | Robert Clotworthy as Announcer
Director: Mark Cendrowski

26 :02x09 - The White Asparagus Triangulation

The relationship between Leonard and Stephanie is going quite well, but Sheldon really likes her and is afraid Leonard isn’t manly enough. Therefore, he decides to create a situation where he needs help from Leonard in order to make him look big in front of Stephanie. However, when his plan backfires, Sheldon becomes so worried that their relationship might end that he goes as far as hacking Leonard’s computer.
Guest Stars: Sara Rue as Stephanie (Dr. Stephanie Barnett)
Director: Mark Cendrowski

27 :02x10 - The Vartabedian Conundrum

When Penny uncovers the truth in Leonard and Stephanie’s relationship, that they are only dating because she likes him, Penny decides to counsel Leonard on the subject. She tells him that his feelings are just as important as everybody else’s, and this gives Leonard the courage to break up with Stephanie… he thinks. After failing to break up several times, he doesn’t know whether to stay in an unsuccessful relationship, or break up and stay single until he can find someone else.
Guest Stars: Sara Rue as Stephanie (Dr. Stephanie Barnett)
Director: Mark Cendrowski

28 :02x11 - The Bath Item Gift Hypothesis

When Leonard meets David Underhill, an award-winning scientist who is the exact opposite of Leonard (handsome, cool and intelligent), Leonard is put in the worst situation he can imagine when David and Penny become more than friends. Meanwhile, Penny buys a Christmas gift for Sheldon, but unfortunately, Sheldon thinks of Christmas as an annoying part of the year where the recipient of a gift is tied to a promise to give the sender a gift back, and Sheldon doesn’t know what to do.
Special Guest Stars: Michael Trucco as Dr. David Underhill |
Guest Stars: Michael Hyatt as Charlotte
Director: Mark Cendrowski

29 :02x12 - The Killer Robot Instability

After Kripke challenges them to a robot duel, the guys build MONTE; a killer robot with many deadly features. But when their robot loses the competition, the guys are humiliated in front of Kripke. Meanwhile, Penny finally tells Howard about his rude behavior towards women, which actually has really, really bad effects on him when he goes into a depression, memorizing all his girlfriend troubles and wondering why he can’t pick up girls.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | John Ross Bowie as Barry Kripke
Director: Mark Cendrowski

30 :02x13 - The Friendship Algorithm

When Sheldon finds out that Kripke is the only person who controls a new supercomputer at the University, Sheldon makes it his mission to befriend Kripke, but due to his problems making friends, Sheldon takes a scientific procedure, which works. However, their friendship may disappear again when it is uncovered that Kripke actually does not have any control of the supercomputer.
Guest Stars: John Ross Bowie as Barry Kripke |
Co-Guest Stars: Will Deutsch as Jeremy | Jane Galloway Heitz as Mildred | Jade Zdanow as Rebecca
Director: Mark Cendrowski

31 :02x14 - The Financial Permeability

After Penny enters a financial crisis, Sheldon lends her money, which she is uncomfortable about. Leonard decides to figure out what the cause of the crisis is, and soon finds out that Penny’s ex-boyfriend Kurt owes her money that he still hasn’t returned. Leonard confronts Kurt with the rest of the guys as back-up, but the plan hits a halt when Kurt gives the money back, but also continues his relationship with Penny.
Guest Stars: Brian Patrick Wade as Kurt
Director: Mark Cendrowski

32 :02x15 - The Maternal Capacitance

When Leonard’s mother, Beverly, comes for a visit, a normal week for the guys and Penny takes a much unexpected turn; Beverly is a neuroscientist who talks to Penny about her problems (making Penny cry like a little girl), Leonard becomes so tired he spends much time in Penny’s apartment (in Penny’s bed… with Penny), Sheldon finds an unusually comfortable person in Beverly, and she believes Rajesh and Howard are in a homosexual sex-relationship.
Special Guest Stars: Christine Baranski as Beverly (Dr. Beverly Hofstadter)
Director: Mark Cendrowski
Songs: Journey -- Any Way You Want It, Red Hot Chili Peppers -- Under The Bridge

33 :02x16 - The Cushion Saturation

Penny finds herself in the worst situation ever when she accidentally shoots a paintball pellet on Sheldon’s cushion, also known as his “spot” on the couch. While she desperately tries everything to fix it, Sheldon is now left with no option rather than to always stand or find another place to sit; much to his dismay. Meanwhile, Leslie and Howard start a sexual relationship together, but he doesn’t know there are no feelings in it, and he asks himself whether or not he likes the idea of being used as a sex object. However, when it turns out Leslie has access to extra grant money which she is willing to give to him so he can continue his research; he becomes really unsure what to do.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski
Story: Chuck Lorre | Teleplay: Bill Prady, Lee Aronsohn

34 :02x17 - The Terminator Decoupling

Aboard a train on their way to San Francisco for a symposium held by Dr. George Smoot, each of the guys has their own separate problems on the train. While Sheldon is desperately finding a way to retrieve his paper he forgot at home, Leonard tries to get some sleep, but it’s difficult with Sheldon’s constant nagging. Meanwhile, Koothrappali and Howard attempt to hit on an actress they spot on the train, but they fight about who should get her and they both destroy one another’s chances at love.
Special Guest Stars: Summer Glau as Herself (Special Appearance by) |
Co-Guest Stars: Dr. George Smoot as Himself | Robert Clotworthy as Conductor
Director: Mark Cendrowski

35 :02x18 - The Work Song Nanocluster

Penny wants to start her own business, making hair clips she calls ”Penny Blossoms”, but she has no marketing, manufacturing or commercial knowledge, and receives help from the guys, especially Sheldon. However, when they get an over-night order with 1000 Penny Blossoms, it’s going to take a lot more than “hard work” to complete the order within the 24 hours they have. Meanwhile, Penny convinces Sheldon into drinking his first cup of coffee, but the results are Sheldon becoming hyperactive and acting as if he was using drugs.
Director: Peter Chakos

36 :02x19 - The Dead Hooker Juxtaposition

Penny feels threatened when a new, very hot girl moves into the apartment right above the guy’s and start using her looks to get help from the guys; fixing stereos and driving her places. Penny, going crazy that she can’t even talk to the guys anymore as they don’t listen to her, understands she has to do something with this new girl, and confronts her. However, the confrontation is a little bit more than just a swear word or two and ends in a chick fight.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Valerie Azlynn as Alicia
Director: Mark Cendrowski

37 :02x20 - The Hofstadter Isotope

When Stuart, the sales clerk at the comic book store, charms Penny completely and gets her to go out with him, everyone is baffled at how he did it. Leonard’s dismay that Penny would go out with Stuart and not him drives him insane, but when an argument between Sheldon and Stuart results in a break-up between Stuart and Penny, Leonard offers his shoulder for Penny “to cry on”. Meanwhile, Howard and Koothrappali head to a women’s bar to pick up girls, and while Howard fails at getting sex, Koothrappali scores… surprisingly.
Guest Stars: Kevin Sussman as Stuart |
Uncredited: Ian Scott Rudolph as Captain Sweatpants
Director: Mark Cendrowski

38 :02x21 - The Vegas Renormalization

When Leslie breaks up with Howard, he becomes so devastated he agrees to go with Leonard and Koothrappali to Las Vegas to cheer him up. But when they arrive, it turns out being a difficult job in itself to get Howard outside the apartment, as all he does is tracking Leslie’s online activities. Meanwhile, Sheldon locks himself out of the apartment back home and much to his and Penny’s dislike spends the night in Penny’s apartment, but he is not able to perform his daily routines and misses home.
Guest Stars: Jodi Lyn O'Keefe as Mikayla
Director: Mark Cendrowski
Songs: Kaley Cuoco -- Soft Kitty

39 :02x22 - The Classified Materials Turbulence

Another date between Penny and Stuart ends in disaster when Penny calls out Leonard's name instead of Stuart's during a make-out. When Leonard finds out, he doesn't know exactly what to do, but his conscience bothers him since he gave Stuart bad advices on how to proceed on the date with Penny. Meanwhile, Howard discovers a big design flaw in his NASA Space Toilet, and needs emergency help from his friends, but it may not be enough.
Guest Stars: Kevin Sussman as Stuart |
Co-Guest Stars: Robert Clotworthy as Astronaut | Travis Davis as Ground Controller |
Uncredited: Ian Scott Rudolph as Captain Sweatpants
Director: Mark Cendrowski

40 :02x23 - The Monopolar Expedition

When Sheldon meets with the University’s Dean, who requests that he leads an arctic expedition to the North Pole, Sheldon asks the guys if they would like to come along. After much consideration, the guys decide to go with him, but they regret it every second during the harsh and cruel training for the extremely cold weather they can be expecting at the North Pole. Meanwhile, Penny hears the news that they’re going away, and decides to show Leonard that she cares about him by knitting him a scarf. However, he believes there may be secret feelings in the scarf, in which she doesn’t want him to go even though she says she will just miss him.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Brian George (1) as Dr. Koothrappali | Alice Amter as Mrs. Koothrappali
Director: Mark Cendrowski
Warning: The Big Bang Theory guide may contain spoilers
Classification: Scripted
Genre: Comedy
Status: Returning Series
Network: CBS ( USA)
Airs: Thursdays at 08:00 pm
Runtime: 30 Minutes
Premiere: September 24, 2007
Episode Order: 24
This guide is currently edited by:
Pentar (Challenge)

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