Book excerpt: Kids can't get enough of laughter--so they can't get enough of Rob Elliot's hilarious joke books! Knock-Knock Jokes for Kids is an all-new collection of knock-knock jokes that will have kids and kids-at-heart rolling in the aisles. Jokes like Knock knock. Who's there? Ben. Ben who? Ben away for a while but I'm back now With more than 2 million copies sold of his first book, Laugh-Out-Loud Jokes for Kids, it's clear that kids (and their adults) are looking for clean, lighthearted humor--and Rob Elliott delivers.