What Goes Up White and Comes Down Yellow?

<p><b>*A brand-new book of amazing, mind-boggling riddles, from the much-loved Gyles Brandreth, author of <i>What's Black and White and Red All Over* </i></b><br><br>When first I appear I seem mysterious,<br>But when I am explained I am nothing serious.<br><br><b><i>What am I?</i></b><br><br>A RIDDLE!<br><br>Was that too easy? How about what goes ninety-nine BONK (a centipede with a wooden leg)? Or which famous book was written by Charles Chickens (Great EGGspectations, of course!).<br><br>In this book you'll find a whole host of amazing riddles. Some will get you head scratching, some will make you laugh, and all are a lot of fun.<br><br>Plus find out some brilliant riddling facts, and top tips on how to solve the trickiest brain-teasers.<br><br>Written by Master of Funny and Collector of Riddles Gyles Brandreth, this is the ultimate, riotous Book of Riddles!<br><br><b>'Very funny and often outright silly' <i>Guardian </i>on <i>Have You Eaten Grandma </i>by Gyles Brandreth</b></p> <p><b>*A brand-new book of amazing, mind-boggling riddles, from the much-loved Gyles Brandreth, author of <i>What's Black and White and Red All Over* </i></b><br><br>When first I appear I seem mysterious,<br>But when I am explained I am nothing serious.<br><br><b><i>What am I?</i></b><br><br>A RIDDLE!<br><br>Was that too easy? How about what goes ninety-nine BONK (a centipede with a wooden leg)? Or which famous book was written by Charles Chickens (Great EGGspectations, of course!).<br><br>In this book you'll find a whole host of amazing riddles. Some will get you head scratching, some will make you laugh, and all are a lot of fun.<br><br>Plus find out some brilliant riddling facts, and top tips on how to solve the trickiest brain-teasers.<br><br>Written by Master of Funny and Collector of Riddles Gyles Brandreth, this is the ultimate, riotous Book of Riddles!<br><br><b>'Very funny and often outright silly' <i>Guardian </i>on <i>Have You Eaten Grandma </i>by Gyles Brandreth</b></p>