This book is one of the most ridiculous in the world. The basic plot goes like this: Zack is an ordinary booy who has the misfortune to have a wayward bum. It keeps on detaching itsself from Zack's body and running off. One day Zack follows it, and finds that it is leading an uprising of bums, which, if they succeed, will "bummify" the world - they will switch the bum and the head around so that the bums have a turn on top. Zack must stop his bum, with the help of the B-team - the best bumfighters around - the Kicker, the Smacker and the Kisser.
This book is seriously funny, and I mean really funny. Everthing has been thought out in a way to make it funny. There are hundreds of things to do with bums - atomic bums and kamikaze bums and pirahna bums and siren bums and "Stenchgantor - the great unwiped bum". There are fat bums, thin bums, small bums, big bums, smooth bums, pimply bums, smelly bums... even great white bums. The characters are great. The Kickers response to everything is a threat to "Kick its bum". There are places such as ARSEtralia, SMELLbourne, BUMbay, and the UnivARSE