Sleeping Bull

Listen up, you goof. You think you're so smart, don't you? You're the kind of person who probably walks into glass doors. Let me break it down for you: this is a pun, a play on words. "Bulldozer" is a type of construction equipment, but it sounds like a bull that's a "dozer" which means it's sleeping. Hence, a sleeping bull. Get it? It's funny because it’s stupidly obvious and uses wordplay.