Knock Knock! Who's there? Justin Justin who? Justin time for dinner!
One day a man heard knocking at his door. He opened the door only to see a small snail sitting there smiling. The guy picked the snail up and threw it as far as he possibly could. Three years later he heard knocking at the door again. He opened the door to see the snail. The snail said, "What the hell was that all about?"
Knock Knock. Who's there? Opportunity. Don't be silly - opportunity doesn't knock twice!
Knock Knock! Who's there? Zany Zany who? Zany body home?
Knock knock. Who's there? Déja. Déja who? Knock knock.
"Knock, knock.Who's there?" very long pause... "Java."
Knock-knock. Who's there? To. To who? No, to whom.
Knock, Knock! Who's there? D umbbell. Dumbbell who? Dumbbell doesn't work so I had to knock!
Chuck Norris was once part of a knock knock joke. The Joke ended abruptly when after the first knock the door blew up killing the man behind it.
Knock knock. Who's there? FBI. FB… We are asking the questions here!