The Best Episodes Written By David Litt

Penny hosts a Halloween party, putting Leonard, Sheldon, Wolowitz, and Koothrappali through a new test of their social skills.

Sheldon's getting fired forces him to explore what life has to offer outside physics, leaving Leonard to take drastic action to snap his friend out of his funk.

Doug can't seem to confront his new neighbors when their dog keeps Doug and Carrie awake all night.

Doug is ecstatic when Arthur moves out of the basement and gets his own apartment following an argument between the two men. But Carrie is saddened by her father's move and wants Doug to ask him to return.