What does Micheal Jackson and a rock have in common?
They are both hard.
Listen up, dummy! You're probably one of those guys who still thinks the Earth is flat. This joke is all about a double meaning. "Hard" can mean difficult, like a tough rock, but it can also refer to, uh, a certain physical state. Get it? Michael Jackson, famous guy, and rock, both can be "hard" in different ways. It's wordplay, you walnut!