A Don King
A Don King is a smug little crook who thinks he's the best thing since sliced bread. He started off stealing from people in a bar and then he became a boss who stole from everyone.
My uncle thinks he's a king, but he just stole my lunch money.
My neighbor thinks he's famous, but he just got a free pizza.
My cousin thinks he's a big shot, but he just got a bad haircut.