"The Zazzy Substitution" is the third episode of the fourth season of the American sitcom The Big Bang Theory. This episode first aired on Thursday, October 7, 2010. Sheldon and Amy break up after Amy says Sheldon's work is not as important as hers. Sheldon then acquires many cats to replace her. Leonard becomes worried and calls Sheldon's mother in order to get Amy and Sheldon back together.