My kids liked a kid version of a previous joke. A man has a pirate squirel living in his backyard and everyday asks him what he's doing. "I'm gathering me nuts for the winter." Next day "Aye, I'm putting me nuts in me tree for the winter."
One day the man looks out and sees a ship's wheel sticking out of the pirate squirel's tree hole, and says "pirate squirel--is that a ship's wheel stuck in your door there?" The squirel says "Aye, it's driving me nuts."
They get the joke but seem to enjoy the idea of a pirate squirel more than the punch-line.