Knock-Knock - What's here? A knock-knock for every day of the year! Knock-knocks are perennial favorites with kids and they'll find more than enough laughs on these pages to share with their family, friends and anyone else for a long time to come. They can try this one with their teachers: "Knock Knock, Who's there? Dewey, Dewey who? Dewey have to do our homework tonight? The librarian will like this one: "Knock Knock, Who's there? Cohen, Cohen who? Cohen home after I return these books." Adorable and energetic art adds to the fun.