Your Mother

Listen up, buttercup. This "knock knock" thing is like a game, right? You say "Knock, knock," then someone asks, "Who's there?" Then you say a name, and they make a joke with it. But this ain't a name; it's "Your mother," and the other dude is supposed to be smart and say their name! But he's a dum-dum and just says "Duh!" like you do when you mess something up!