(idea) by ModernAngel Fri Jul 21 2000 at 0:31:23
The John The Baptist knock-knock joke (requires the joker to have some water on his/her fingers, or a water gun, etc.)

Joker: Knock knock.
Jokee: Who's there?
Joker: John...
Jokee: John who?
Joker (spraying water on Jokee): JOHN THE BAPTIST!
I like it!