Knock knock. Who's there? Déja. Déja who? Knock knock.
Knock knock. Who's there? Kenya. Kenya who? Keeeenya feeel the loooove tonight?
"Knock, knock.Who's there?" very long pause... "Java."
Knock, knock Who's there? I'm Mr, Farter. Mr, Farter who? I've brought some insecticides to give to your mother in law!
Knock, knock! Who's there? Opportunity! That is impossible. Opportunity doesn't come knocking twice!
Knock knock. Who's there? Sarah. Sarah who? Sarah problem here?
Knock-knock. Who's there? To. To who? No, to whom.
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!
Fan: "I see you won a silver medal at the Olympics. What's it for?¨" Athlete: "It's for telling knock knock jokes." Fan: "And what's that gold medal for?" Athlete: "For stopping."