The Tough Guide to Fantasyland by Diana Wynne Jones

If you want something to joke about with your friends and they're into fantasy, this is the thing for you. It's hilarious and pokes immense fun at the cliches and often over used ideas prevalent in the Fantasy industry. Just try finding an old book that doesn't at least incorporate one of these things... I dare you. >:D

It's not really a story book so if you're looking for a story try reading 'The Darklord of Derkholm' which tries to incorporate some of these aspects Jones mentions - that novel is also by her. It's not necessary reading, but the two sort of compliment each other in a way. :)