You're too much!
Expresses a mixture of surprise and admiration of behavior that is considered extreme or well beyond expected social norms; generally to express praise and shock at another person's capacity to be balsy.
Boy: So you're going to accept the diamond engagement ring and not give it back after you dump him?
Girl: Well of course I'm waiting to get the ring; otherwise I would have already dumped him. Duh!
Boy: You're too much!
Girl: Well of course I'm waiting to get the ring; otherwise I would have already dumped him. Duh!
Boy: You're too much!