Everybody enjoys language play or plays with language for themselves. And that's why you tell the joke. Not necessarily to get a laugh, although it's nice if it happens. People enjoy the encounter they've had with you and go away thinking, ah, I really enjoy that. We're all humorous, really. So it's a third important underlying principle of life. It would depend on the language but in our culture, it is a very important teacher as I've tried to explain in the language acquisition context.