The "Sheldon the Zombie" scene arrives at the end of the episode "The Good Guy Fluctuation" in which Leonard and Priya's relationship ends, but let's cut through all that complicated dating stuff and get straight to the humour. After being pranked by the gang at Halloween, Sheldon decides to take revenge, but all his pranks fail. Leonard reverses his airbag prank on him, Raj enjoys the company of the snake Sheldon hid in his top desk drawer, and Howard pretends he has a heart condition and scares Sheldon further when he attempts to trick him with an electric handshake. In the end, Sheldon gets his revenge on Leonard, who, reeling from the news that Priya had an affair, is scared out of his mind as a zombie-clad Sheldon pounces from under a sofa cushion.