The Big Bang Theory, The Lunar Excitation

Discovering Leonard, Raj and Howard fudged the results of his Arctic research expedition, a disgraced Sheldon heads home to Texas.

Sheldon and Howard wager comic books over a cricket's species. Meanwhile, a less-than-perfect romantic night agonises Leonard and Penny.

Howard takes Raj along to check out the Goth dating scene. Sheldon uses chocolate as part of a behaviour modification experiment on Penny.

Facing a return to India, Raj needs a job desperately enough to consider working for Sheldon. Meanwhile, Howard becomes a third wheel to Leonard and Penny.

Sheldon looks forward to squaring off against an actor from the Star Trek universe he holds enmity towards in a fantasy card game tournament. Wolowitz cashes in on an old pact with Leonard to get Penny to set him up with a friend of hers.

Leonard, hoping to fit in with Penny's football-loving friends, gets tutored in the sport by Sheldon. Raj is infuriated when Wolowitz's skirt-chasing leads to the loss of his prized patang.

Leonard and Penny's first big fight sees Sheldon playing mediator due to childhood trauma that's left him with an inability to be around loud verbal conflicts.

With the rest of the gang off on a desert camping trip to view the Leonid meteor shower, Sheldon must play hero after Penny slips in the tub and dislocates her shoulder.

Barry Kripke pranks Sheldon during his spot on NPR, leaving him with a taste for vengeance. Wolowitz, pressured by Bernadette to define their relationship, gets advice from a fantasy version of Katee Sackhoff.

Penny seeks Sheldon's help to better comprehend Leonard's physics work. Wolowitz sees green when Leonard invites Bernadette to watch an experiment.

A Christmas visit from his mother has Leonard discovering she's kept a lot of news from him that she shares with Sheldon and worrying if she'll approve of his romance with Penny.

Leonard is aghast to find out a secret of Penny's: she believes in psychics. Meanwhile, Sheldon tries to assist Koothrappali in picking up a girl at a university party.

A robbery of their apartment sees Leonard and Sheldon call on their friends to devise a security system.

Stuck on the solution to a physics problem, Sheldon seeks a number of alternative approaches to change his thinking and free the mental block -- including working with Penny at The Cheesecake Factory.

When Leonard is offered a trip to Switzerland on Valentine's Day to see a particle accelerator, he must choose between taking Penny or Sheldon.

An appearance in traffic court comes at the worst possible time for Sheldon, the same day Stan Lee is appearing at the comic book store.

The guys go to a garage sale and find a ring from the Lord of the Rings films, and the rare find threatens their friendship.

Sheldon's fear of speaking in front of large groups threatens his ability to accept an award, so the gang tries to help him get ready for the big night.

Sheldon gets to square off at the bowling alley against nemesis Wil Wheaton. Meanwhile, Leonard's miffed when Penny doesn't respond the way he hoped after saying 'I love you.'

Subsequent to Leonard and Penny's break-up, Sheldon tries to hide from Leonard and the gang that he had a friendly spaghetti dinner at Penny's.

Sheldon hosts a visiting female physicist, but her intelligence seems matched by her libido.

A squabble over the thermostat setting leads to Leonard going over to Penny's and recounting for her the story of how he met and moved in with Sheldon.

Howard and Raj try to find the perfect match for Sheldon by setting him up on an Internet dating site. Seeing her new boyfriend interact with the gang makes it clear to Penny that she can't go back to dating dumb jocks after dating Leonard.