The Big Bang Theory

When Penny moves in across the hall, socially awkward scientist Leonard is instantly smitten, much to roommate Sheldon's dismay.

Leonard offers to receive a package on Penny's behalf, but things go awry when Sheldon feels the need to clean her apartment.

Leonard is devastated when he sees Penny kissing another man, and he asks her out on a date under the guise of a group dinner with the guys.

Leonard calls in Sheldon's mother when Sheldon becomes obsessed with weaving ponchos and illuminating fish after being fired from his job.

After agreeing to a sexual encounter with Leslie, Leonard becomes upset when he learns she was only interested in him as a one-night stand.

The guys go well outside their comfort zone when they accept an invitation to Penny's Halloween party, where Leonard has a run-in with Penny's ex.

When Penny's friend hooks up with Howard in her apartment, Penny has to crash with the guys ... and becomes the fourth member of their Halo team.

After being set up on a date, shy Raj realizes he's able to talk to women if he's drinking. But he gets too wasted and his date leaves with Sheldon.

Leonard and Sheldon are invited to an academic conference to present research they conducted together, but Sheldon doesn't want to participate.

Leonard and Sheldon lie to avoid Penny's singing, but Sheldon takes the ruse too far when he invents a cousin with serious personal problems.