Knock, Knock

West loves to tell knock knock jokes. He doesn't really get the JOKE part of it though. Here's one he told me last night:

Knock knock
Who's there?
Mommy tiger
Mommy tiger who?
Mommy tiger eats pillows

Then he laughs hysterically, like it's the funniest thing he's ever heard. I can tell that you are laughing hysterically too.