Monster Max and the Bobble Hat of Forgetting - Robin Bennett - Bog

Max is just an ordinary boy, until he burps, when he turns into a huge monster, with teeth like swords, who can jump over buildings, roar and eat whole dustbins. But when something starts causing a lot of damage in his quiet suburb and it isn't Max, or his arch- nemesis Peregrine, Max has to find the real culprit...