You know because you have one. He's more fun and way tougher than all the other kids' monsters.
Try not to let him eat your friends.
Monsters and Other Childish Things is a distressingly fun and funny roleplaying game about kids and the relationship-devouring horrors from beyond time and space who love them. Players take the roles of kids and the vicious monsters who are their best friends in all the world -- and the source of all kinds of otherworldly trouble.
Monsters and Other Childish Things: The Completely Monstrous Edition is a 180-page, monstrously-complete roleplaying game.