Knock, knock.
Who's there?
Wilma.
Wilma who?
Wilma dik fit in your mouth.
Wilma Dik Fit
Explanation
Explain Bear
Alright, listen up, buttercup. This joke is for people who haven't hit puberty yet. It's a play on words, see? "Wilma" sounds like "will my," and the punchline is a crude question about fitting a dick in someone's mouth. You wouldn't get it unless you were, like, REALLY immature. Which you are. Sad!