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Season 2
23 Episodes2008
This season, Leonard gets a girl. So does Sheldon. Howard drives the Mars Rover into a ditch. Raj woos a terminator. Gorgeous girl-next-door Penny falls under the spell of Age of Conan. And super-smart, ueberconfident Leslie Winkler reduces mere men to spineless jellyfish.
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Episodes (23)

Ep 1
The Bad Fish Paradigm
★7.8
2008-09-22•22m
Penny's first date with Leonard goes awry; Penny finds Sheldon to be an unwilling confidant.

Ep 2
The Codpiece Topology
★7.6
2008-09-29•21m
A jealous Leonard reacts to Penny's new guy by rebounding with Leslie.

Ep 3
The Barbarian Sublimation
★7.9
2008-10-06•21m
Sheldon creates a monster when he introduces Penny to online gaming.

Ep 4
The Griffin Equivalency
★7.6
2008-10-13•21m
Raj gets an inflated ego and makes a play for Penny after being referenced in a magazine article.

Ep 5
The Euclid Alternative
★7.6
2008-10-20•20m
Leonard and his friends stage an intervention to force Sheldon to face his fear of driving.

Ep 6
The Cooper-Nowitzki Theorem
★7.8
2008-11-03•21m
Sheldon and the gang are confused when a young grad student is attracted to him.

Ep 7
The Panty Piñata Polarization
★7.9
2008-11-10•21m
When Sheldon bans Penny from the apartment for numerous minor infractions, she decides to retaliate.

Ep 8
The Lizard-Spock Expansion
★7.4
2008-11-17•20m
Leonard inadvertently steals away the new woman Wolowitz thinks is the love of his life.

Ep 9
The White Asparagus Triangulation
★7.4
2008-11-24•21m
Sheldon is thrilled when Leonard starts dating a woman who meets Sheldon's stringent standards.

Ep 10
The Vartabedian Conundrum
★7.0
2008-12-08•21m
Leonard asks Penny for advice when his new relationship starts moving too fast.

Ep 11
The Bath Item Gift Hypothesis
★8.2
2008-12-15•21m
Penny starts dating Leonard's handsome colleague; Leonard and his friends are tortured by Sheldon's obsession with gift-giving etiquette.

Ep 12
The Killer Robot Instability
★7.5
2009-01-12•21m
Penny's criticism of Wolowitz's romantic life pushes him into depression and AWOL for a fighting robot battle the rest of guys are depending on him for.

Ep 13
The Friendship Algorithm
★7.5
2009-01-19•21m
Sheldon creates a scientific procedure for making friends.

Ep 14
The Financial Permeability
★7.4
2009-02-02•21m
Sheldon's solution to Penny's financial difficulty leads to a confrontation between Leonard and Penny's ex-boyfriend.

Ep 15
The Maternal Capacitance
★8.2
2009-02-09•21m
Leonard and Penny are drawn together after a disastrous visit from Leonard's mother.

Ep 16
The Cushion Saturation
★7.5
2009-03-02•21m
A paintball game leads to a fight between Sheldon and Penny, and romance for Leslie and Wolowitz.

Ep 17
The Terminator Decoupling
★7.6
2009-03-09•21m
Leonard, Sheldon and Wolowitz are ecstatic to learn that a famous science-fiction actress (Summer Glau) is on board the train they are taking to San Francisco.

Ep 18
The Work Song Nanocluster
★7.6
2009-03-16•20m
Penny's home business turns into a complete nightmare when Sheldon takes over.

Ep 19
The Dead Hooker Juxtaposition
★7.6
2009-03-30•20m
Penny squares off with a new beautiful female neighbor who may become the building's "new Penny."

Ep 20
The Hofstadter Isotope
★7.6
2009-04-13•20m
A fellow comic book enthusiast's hitting on Penny leads to Leonard and Howard going to a bar's Ladies' Night.

Ep 21
The Vegas Renormalization
★7.5
2009-04-27•22m
Leonard and Koothrappali escort a heartbroken Wolowitz to Las Vegas, and Sheldon becomes locked out of his apartment and must stay with Penny.

Ep 22
The Classified Materials Turbulence
★7.5
2009-05-04•19m
Penny's second date with Stuart sees her making a comment that gives Leonard new hope for a relationship with her. Wolowitz realizes there's a crucial error in a NASA project he's working on.

Ep 23
The Monopolar Expedition
★7.5
2009-05-11•21m
The guys' plan to work over the summer at the North Pole makes Penny revaluate her feelings for Leonard.