* 'What do you call a flock of sheep rolling down a hill? A lamb-slide!' With page after page of hilarious one-liners, riddles, knock-knock jokes, tongue twisters, and illustrations, Silverthorne's latest joke book is sure to bring your 6- to 12-year-olds hours of laughter---and a lifelong sense of humor. 144 pages, softcover from Revell.