Dog People deserve Dog Jokes! Get your dog-loving little one laughing with this collection of illustrated dog jokes! Knock Knock, Woof Woof is filled with funny jokes for kids celebrating dogs and all of their pup-tastic perfection. Each page features one illustrated joke. Here's a silly sample: What dog keeps the best time? A watch-dog! Knock Knock, Woof Woof is part of the Illustrated Jokes series. Other titles include: Fart-tastic Too School for Cool Knock Knock, Boo Who? Knock Knock, Moo Who? It's Snot Fair! Knock Knock, Lettuce In! Knock Knock, Blub Blub! Wait, What? Knock Knock, Olive You Yo Ho, Ha Ha Knock Knock, Jingle Jingle Knock Knock, Meow Meow Knock, Knock, Play Ball! and more!