Among Mark Twain's essays, I like "The Awful German Language" and "How I Edited an Agricultural Paper." Among his short stories and sketches, "Buck Fanshaw's Funeral" and "The Blue Jay Yarn." "Innocents Abroad" is hilarious in places. "Huckleberry Finn" is not all funny, but it can be appreciated on many levels, and can be read several times during a lifetime. It's not too early to start now.

I agree that "Catch-22" is the world's funniest novel, but I'm afraid much of the dark humor will be over the heads of kids. It's all about hypocrisy, really.