The joke's on you

I have this new favorite joke. It was on Prairie Home Companion over the weekend. But it's very difficult to retell.

See, it's a knock-knock joke, and it goes like this:

Knock knock
Who's there?
Control freak. Now, you say "control freak who?"

People seem to get tripped up and say "control freak who?" And that just ruins the joke.

My wife says it's up there in funniness with the feminist light-bulb joke:

Q: How many feminists does it take to change a light bulb?
A: That's not funny.

Ah, intellectual humor.