Amy: Sheldon, I am not doing Fun with Flags with you.
Sheldon: Why not?
Amy: Because we're broken up!
Sheldon: Sonny and Cher made it work. Their variety show kept going long after the divorce, and here we are still talking about them.
Amy: No one's talking about Sonny and Cher.
Sheldon: You must be thinking about Donny and Marie, because you and I are clearly talking about Sonny and Cher.