Knock Knock.
–Who’s there?
Cow go.
–Cow go who?
No, Cow go moo.
Another one: you say, “Hey, wanna hear a good knock-knock joke?”
The predictable response: “Okay.”
You say, “Okay, you start.”
So they say, “Umm…… knock-knock?”
You say nothing. Just look at them and wait.