Film review: The Great Hip Hop Hoax (18) Get rich or try lying. This documentary tells of an imposture that one feels could only have been perpetrated on the music industry. Californian hip-hop duo Silibil and Brains arrived in London, signed a deal and looked set for stardom. Only they weren't from California, they were two Scottish students, Billy Boyd and Gavin Bain, who got fed up with rejection and decided on a whim to "go American," accents and all. Record company executives who were taken in look back wryly on their gullibility. Camcorder footage of the two rapping pranksters acting like arses doesn't encourage sympathy, though interviews with the grown-up Billy and Gavin present a more thoughtful and chastened pair: there's a sense of bemusement that they managed to get so far. It's a good story, though it could have been told more cogently inside an hour. It also illustrates how as a rapper you don't have to do a great deal to be mistaken for the "real" thing.