A joke is not a thing but a process, a trick you play on the listener's mind. You start him off toward a plausible goal, and then by a sudden twist you land him nowhere at all or just where he didn't expect to go.
“No one who set out to design a form of communication would ever end up with anything like English, Mandarin, or any of the more than six thousand languages spoken today.”
“I began with dance, doing ballet at 3, then tap, jazz, modern. Then I sang in church choirs, learned how to play clarinet and drums, sang with rock bands and only then did I get into musical theatre.”