In countless interviews over the last twenty five years, creator Matt Groening has described The Simpsons as ''a show that rewards you for paying attention.'' Certainly, there are more jokes crammed into a typical episode than most sitcoms can stretch over an entire series. Some are smart, some are silly and some are just plain surreal- but the hardest task is in trying to spot every single one. With a seemingly endless list of characters and literally hundreds of quotable lines, The Simpsons not only stands up to repeated viewings but actually grows stronger from them. If you return to an episode, you're guaranteed to laugh at something that you missed the first time around. After all, to quote Ben Stiller in Extras, it's layered- it's made like that. As much as you scrutinise all corners of the screen, it's practically impossible to catch every Church of Springfield sign, every company slogan or every newspaper headline in one viewing. So what about the jokes that slipped through the net? The background banners that passed you by? The throwaway gags that both require and reward an encyclopaedic knowledge of almost every aspect of the show? The lines that, in order to appease the censors, were cut short by a word or even a syllable, leaving it to the fertile (and often filthy) minds of the viewers to fill in the gaps? Well, chances are they've been rounded up and bundled together in this easy-to-digest list. Let's crack on, shall we?