Sheldon wins a grant to pay for a summer expedition to the North Pole, and invites his friends...
Stuart takes Penny out for a second date, during which she drunkenly reveals her true feelings....
Leonard and Raj take a heartbroken Howard to Las Vegas, where they pay a prostitute to spend...
Penny catches the eye of a comic-book shopkeeper, and Leonard is devastated when she gives...
Penny feels threatened when another sexy woman, who has landed a role in TV series CSI, moves...
Penny starts her own hair accessories business, but makes the mistake of asking Sheldon to help...
Leonard, Sheldon, Howard and Raj discover actress Summer Glau is on their train while...
Tensions between Sheldon and Penny reach a high after a paintballing accident leaves an ugly...
Leonard and Penny share an intimate moment as they recover from a psychological deconstruction...
Penny runs into money troubles, so Sheldon offers to lend her some cash to help her pay the...
Sheldon decides to put his formidable brain power to use in devising a scientific procedure for...
Sheldon and the gang are excited when Barry Kripke challenges them to a robot duel. Meanwhile,...
Sheldon's obsession with gift-giving etiquette annoys his friends as Christmas approaches....
Leonard turns to Penny for advice when his relationship with Stephanie takes off faster than he...
Sheldon is delighted that Leonard has finally managed to find a girlfriend who meets his high...
A smitten Howard becomes convinced he has met his soulmate in the form of surgeon Stephanie...
Penny's TV breaks down, so she visits the boys' flat to watch her favourite shows. However,...
Sheldon acquires a girlfriend, who soon expresses distaste for his social life, and removes him...
Sheldon is forced to confront his fear of driving when both Penny and Howard refuse to give him...
Elated at being named one of People magazine's `30 to Watch Under 30', Raj makes a pass at...
Penny becomes addicted to an online game based on the world of Conan the Barbarian. As her...
Leonard is dejected to see Penny with another man and decides to cut his losses by going back...
Sheldon finds himself forced to keep a secret when Penny decides to tell him what happened on...