The Day My Bum Went Psycho

Blurb

The Day My Bum Went Psycho is a novel for children by Australian author Andy Griffiths. "Bum" is a slang word used in many English-speaking countries for the buttocks; in North America the term "butt" is used instead, and the book is published there under the title The Day My Butt Went Psycho.
The protagonist is a boy called Zack Freeman who has to seek the help of some "bum-hunters" to catch his bum after he learns it is actually the leader of a band of rogue bums determined to control the world. It is illustrated by Nicole Arroyo, who also illustrated some of Andy Griffiths' other books, including the Just! series.
The Day My Butt Went Psycho! is a Canadian-Australian animated TV series based loosely on the novel, and its sequels, first shown on Australian channel Nine Network in September 2013 and on Canadian channels Teletoon and Télétoon in June 2014.