This film about the trials and tribulations of the "World's Loudest Band" would deserve a spot on this list simply by virtue of how funny it is. Few films are this quotable, or this consistently clever (or stupid, since theres a fine line between the two). But what really makes the film a masterpiece is how fully-realized Spinal Tap really is- there's never a time when Spinal Tap doesn't feel like a convincing band, and indeed the film's stars toured a number of times as Tap after the film was released. THIS IS SPINAL TAP perfected the format of the "mockumentary", a goof on documentary style which would be impossible if the filmmaker and his actors hadn't so completely figured out their characters and their mythology. We watch the film and while we know that SPINAL TAP was a fictional band at the time, the film convinces us that they could be real, which makes everything even funnier. Really, the comedy gets turned up to eleven, and if you don't know what I'm talking about, see the film.