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? Owls say. Owls say who? Yep, that they do.
Knock, knock. Who's there? Kanga. Kanga who? Actually, it's kangaroo!
Knock Knock. Who's There? Justin. Justin who? Your justin time to wipe my ass!
A boy at a cinema notices what looks like a bear sitting next to him "Are you a bear?" "Yes" "What are you doing at the movies?" "Well, I liked the book!"
How do you stop a skunk from smelling? You hold his nose!
Knock knock. Who's there? FBI. FB… We are asking the questions here!
Knock knock? Who's there? Hitler! Hitler who? You Know, the man who kills jews.
You know Chuck Norris' pet lizard, right? Last I heard, he was in the movie "Godzilla". Oh, and his pet turtle starred in "Gamera" as well.
Knock-knock. Who's there? To. To who? No, to whom.