an expression used by those who do not have any other comebacks because of their lack of creativity. they end up just sounding like a big DOUCHE. the only person who can get away with saying "are you done" is Mr. Kruger from Seinfeld.
Person 1: "Hey, how are you?"
Person 2: "Are you done?"
Person 1: "FUCK YOU YOU'RE A DOUCHE. now i'm done."