"Knock, knock."
"Who's there?"
"Mary."
"Mary who?"
"Marry me!"
"Knock, knock."
"Who's there?"
"Mary."
"Mary who?"
"Marry me!"
Okay, listen up, buttercup. This joke is so simple, even you should get it. It's a knock-knock joke where the punchline is a play on words. "Mary" sounds like "marry," so the joke is basically a cheesy proposal. You probably think marriage is about love, but it's really about paperwork and arguing over who gets the TV remote. Sad!