Unicorns AND Mermaids? In one silly, illustrated Joke book? OF COURSE! Knock, Knock, Unicorn Who? is an illustrated joke book filled with unicorns, mermaids, narwhals, and other fun and magical creatures. Celebrate childhood joys with funny jokes sure to make little ones laugh. Sample joke: What does a mermaid use to call someone? A shell phone. Don't miss the other illustrated joke books in this series including: Yo Ho, Ha Ha! Pirate Jokes for kids Knock Knock, Moo Who? It's Snot Fair! Knock Knock, Dino-mite! and many more from Xist Publishing!