Jokes Heard from the Backseat...

Picking up E from preschool, we have our friend JK with us. E, JK and A are in the backseat telling knock knock jokes that I'm trying to steer away from the riotous punchlines of things like "poopy diapers" and "toilets." A tells JK the following:

"Knock Knock"
"Who's there?" he asks.
"Cow."
"Cow who?"
"Cows don't say who, they say 'mooooooooooooooo'."

For some reason, even though it's admittedly cringe worthy, I thought it was pretty funny for a 5 year old to come up with.