Original Air Date—8 December 2008
Leonard is the last one to realize that Stephanie has moved in with him. And when he finds out, he becomes worried that they are moving too fast
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Season 2, Episode 11: The Bath Item Gift Hypothesis
Original Air Date—15 December 2008
Much to Lenonard's disappointment, Penny suddenly develops an interest in science when a sexy new physicist joins the lab. Meanwhile, Sheldon struggles to find an appropriate Christmas gift for Penny.
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Season 2, Episode 12: The Killer Robot Instability
Original Air Date—12 January 2009
Howard becomes depressed after Penny makes a cruel statement about his love life, while the rest of the guys prepare for a grudge killer robot duel against an obnoxious colleague at the university.
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Season 2, Episode 13: The Friendship Algorithm
Original Air Date—19 January 2009
Sheldon tries to make friends with a despised colleague, with the hopes that it will get him access to a coveted computer in the lab.
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Season 2, Episode 14: The Financial Permeability
Original Air Date—2 February 2009
Penny cannot afford to pay her rent, so Sheldon and Leonard each come up with unique ways to help her out.
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Season 2, Episode 15: The Maternal Capacitance
Original Air Date—9 February 2009
Sheldon hits it off with Leonard's psychoanalyst mother, but she drives Leonard and Penny to the bottle.
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Season 2, Episode 16: The Cushion Saturation
Original Air Date—5 May 2009
Howard hooks up with Leslie, while Penny accidentally ruins Sheldon's spot on the couch.
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Season 2, Episode 17: The Terminator Decoupling
Original Air Date—9 March 2009
On a train trip to San Francisco, the boys debate on how to meet sci-fi star Summer Glau, who is on board with them.
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Season 2, Episode 18: The Work Song Nanocluster
Original Air Date—16 March 2009
Sheldon's assistance with Penny's home-based business leads to disaster.
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Season 2, Episode 19: The Dead Hooker Juxtaposition
Original Air Date—30 March 2009
Penny becomes jealous when a gorgeous new neighbor attracts the guys' attention.
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Season 2, Episode 20: The Hofstadter Isotope
Original Air Date—13 April 2009
Leonard is so upset when a friend from the comic book store begins dating Penny that he convinces Howard and Raj to take him to a bar so that he can pick up a woman of his own.
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Season 2, Episode 21: The Vegas Renormalization
Original Air Date—27 April 2009
After being dumped by Leslie, Howard heads to Las Vegas with Leonard and Raj, leaving Penny to deal with Sheldon, who has locked himself out of the apartment.
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Season 2, Episode 22: The Classified Materials Turbulence
Original Air Date—4 May 2009
Penny's second date with Stuart has significant implications for Leonard. Howard enlists the guys' help with one of his NASA projects.
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Season 2, Episode 23: The Monopolar Expedition
Original Air Date—11 May 2009
Penny gets upset when she finds out Leonard and the guys plan to work at the North Pole for the summer.
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