While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.

Leonard tells Penny about how he met Sheldon for the first time...and what happened to the elevator.

Leonard and Sheldon compete for the attention of a famous female physicist.

When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy.

A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.

Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award.

When the guys find a ring from "The Lord of the Rings" at a garage sale, it threatens to tear them apart.

An appearance in traffic court jeopardizes Sheldon's chance to meet Stan Lee.

Leonard faces a dilemma in choosing between Sheldon or Penny to accompany him to Switzerland to see CERN's Large Hadron Collider on Valentine's Day.

Sheldon ends up working with Penny at The Cheesecake Factory to help solve a physics problem.

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

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.

Leonard fears the worst for his relationship with Penny when his mother visits, while Sheldon is nothing but thrilled with Beverly's presence.

Penny seeks Sheldon's help to better comprehend Leonard's physics work. Wolowitz sees green when Leonard and Bernadette become pals.

Barry Kripke embarrasses Sheldon on NPR, and the gang rallies to help him get his revenge. Wolowitz, desperate to keep his romance with Bernadette alive, gets advice from a fantasy version of Katee Sackhoff.

With the rest of the gang off on a desert camping trip, Sheldon must play hero to an injured Penny.

A squabble between Leonard and Penny sees Sheldon playing mediator, though out of his own incovenience from the sitiation rather than altruism.

Leonard gets tutored in understanding football by Sheldon, while a kite mishap puts a rift between Wolowitz and Raj.

Sheldon squares off against the the one actor from the Star Trek universe he holds enmity towards: Wil Wheaton. Wolowitz wants Penny to set him up with a friend of hers.

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.

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

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

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