Knock, Knock.Whos There?Luke.Luke Who?Luke Through The Keyhole!If You Love Knock Knock Jokes, Then This Is The Book For You! Its Packed With Hilarious Illustrations And Over 400 Witty Wisecracks. Youre Guaranteed To Be Doubled Over With Laughter By The Time Youre Finished! Perfect For Children Aged 7+.About The Series: Arcturus Publishings Best Ever Series Brings Together A Wonderful Array Of Puzzle Books, Activity Books And Joke Books To Keep Children Entertained For Hours!