I Don't Know, Can You
A simple phrase, but usually uttered by trash human beings. Usually it is a sarcastic response after someone says "Can I ....... (Enter More Sentence Here)?" If someone says this near you, you may want to exclude them from your friend list.
Person 1: "Can I get a drink of water?"
Person 2: "I don't know, CAN YOU?"
Person 2: "I don't know, CAN YOU?"