May is National Smile Month -- to celebrate I had everyone do a "Knock Knock" joke for you!

You remember the jokes as a kid or play them with your child.  The standard format has five lines:

The joke-ster: Knock, knock!

The recipient: Who's there?

The joke-ster: A response, sometimes involving a name (Doctor)

The recipient: A repetition of the response followed by who? (Doctor who?)

The joke-ster: The punch line, which typically involves a "punnish misusage" of the word set up during the response (How did you know?!)
After the jump -- check our our corny fun!

The joke refers to the situation where someone knocks on a door and identifies to get somebody who is already inside to open the door, even though there are usually no doors involved when this joke is told.