The Big Bang Theory – Season 3, Episode 21

G The boys return from their freezing research trip to the North Pole, and Penny and Leonard finally give in to temptation but must then deal with the awkwardness that follows.

PGR Leonard and Penny struggle to recover from an awkward first hook-up, while Sheldon and Howard stake their best comic books on a bet to determine an insect species.

G Howard and Raj visit a Goth nightclub to pick up women, while Sheldon attempts to build a better Penny using chocolate-based behaviour modification.

G Raj must find a new job or be sent back to India. However, Sheldon has a solution that leaves Leonard and Penny dealing with Howard as third wheel.

PGR While Sheldon settles a score with his nemesis, Star Trek's Wil Wheaton (guest starring as himself), Wolowitz begs Leonard to get Penny to set him up with one of her friends.

G Sheldon teaches Leonard how to understand football, and a kite-flying incident threatens Howard and Raj's friendship.

G Sheldon finds Leonard and Penny's argument to be inconvenient, and is forced to play peacemaker.

G With Leonard, Howard and Raj away camping in the desert, an injured Penny has only Sheldon to rely on.

PGR After he's humiliated on public radio, Sheldon vows to destroy Kripke, while Wolowitz tries not to destroy his new relationship with Bernadette.

G Sheldon takes on his greatest challenge when he attempts to help Penny understand physics, and Wolowitz becomes jealous when Leonard starts hanging out with his new girlfriend.