Knock knock!
Who's there?
Police.
Police who?
Police open the door -- I forgot my lunch!

Where does the catcher sit for dinner?
Behind the plate.

Why did the invisible man look in the mirror?
To make sure he still wasn't there.

How do you know when there's a elephant under your bed?
Your nose is pressed against the ceiling.

What do you get when you cross an elephant with a jar of peanut butter?
An elephant that sticks to the roof of your mouth.