"Eric" - Demonology, three wishes and the Hell of Bureaucracy
No one points out how arbitrarily we sort our World quite like Terry Pratchett. He always writes the kind of books that make you keep on saying 'I see what you did there.' And Rincewind, the wizard who keeps on running with his invincible luggage, is always a favourite :D This time he's in the strange position to grant a demonologist three wishes and that works out about as well as expected... Big fun :)
Eric: Discworld: The Unseen University Collectionvon Terry PratchettGollancz