The Simpsons are the most famous family on television - and the long-running 20th Century Fox animation arguably has one of the most iconic openings to their show. After the blue skies and parting clouds give way, we're dropped into the wonderful world of Springfield, where we see Bart at school writing lines on the blackboard, before breaking loose on his skateboard and riding home, creating havoc along the way. Bart's blackboard jokes get the most attention initially, but it's the recurring 'couch gag' theme that most fans associate with when they think of the program. There's been more than 270 different 'couch gags' in the show's near quarter-century run, and ever since the first aired on our screens in the 1990 episode 'Bart the Genius', fans have been treated to an eclectic variety. From the evolution of man through to nods at popular culture, even some of the world's best-known celebrities have been getting in on the act, with Guillermo del Toro famously trying his hand at a couch gag earlier this year for a special "Treehouse of Horror" episode. And here, we take a look at the 20 Greatest Couch Gags from the Simpsons so far. Click "Next" to get started.