Knock knock--who's there? A book filled with hilarious one-liners and surprises! This book will introduce readers to knock-knock jokes on a wide variety of high-interest subjects, from space to dinosaurs. Fact boxes on each spread will spark readers' interest, as the accompanying jokes make them laugh out loud. Colorful images and a bright design will catch readers' eyes, as they play with language and the element of surprise. Readers are sure to find a laugh behind every door--and on every page.