The googly-eyed animals in Rob Hodgson's Knock Knock: Merry Christmas! , a book of Christmas knock-knock jokes will have kids laughing all the way through holiday season! Knock, knock! Who's there? Meet a snowman, a reindeer, an elf, and more in this interactive joke book full of holiday fun. With each knock on the door, join our cat host in asking, "Who's There?" before turning the page to discover a different googly eyed Christmas guest and their giggle-worthy punchline. This easy-to-follow first joke book is packed with Christmas hilarity sure to make the whole family merry. Googly-Eyed Joke Book series Knock Knock: Who's There? Knock Knock: Merry Christmas!.