waiter... What would you like for DESSERT this evening...?
Dumbass... UR MOMMM!!!!!!!
waiter... How much of a tip are you goin to leave...?
Dumbass... A big one... in UR MOM!!!!!!!!!!!!!!!!!!!!!!!!!!
said as a filler, used as a sarcastic retort to something obnoxious, meaning most likely to shut the hell up and stop talking, or take the direction of the conversation a different way.