You can, as a family, tell Knock-Knock jokes for half an hour straight and laugh your ass off.
I think my favorite one that Jet came up with out of the mass was:
I'm not exactly sure what connection did it, but John was trying to explain allergies to Jet, and how when some people eat some things they'll get a rash and itch and other people find it hard to breath and...
Jet suddenly lit up and said, "Ohhhh! It's JUST like when vegetarians don't eat vegetables that begin with P!"
John died laughing. I didn't do much better. I have just the vaguest of ideas where this connection might have been made, but it had to do with a game where a pictured hippo was a vegetarian and could only eat foods that began with P and you had to circle the what the hippo could eat... but I'm not at all sure where he got the allergy connection to it. Hm.
Anyway... I am amazed by kid's dendrite connections that aren't pruned, yet.