Extras: Where the elite meet to self-depre-keet. (It works with a British accent. Really.) Ricky Gervais, who launched his scathing HBO showbiz satire with cameos by an imperious Ben Stiller and a slatternly Kate Winslet, has now handed the bloody scourge to rock stars. In these previews, Coldplay's Chris Martin plays Coldplay's Chris Martin as a dead-eyed opportunist hawking his greatest hits album at a charity shoot for third-world poverty. ''Let's get on with it,'' snaps Martin (pictured, right, with a bewigged Gervais), ''I've got AIDS and Alzheimer's after this, and Gwyneth’s making drumsticks.''
But that's but sauce to the goose -- the goose, in this case, being David Bowie, Rock Star Cameo extraordinaire. A conversation with Gervais' sad-sack writer/actor, Andy Millman, launches Bowie into reverie. He turns to a Simpsons-convenient piano and begins composing a song called ''Little Fat Man,'' which soon expands into a giant singalong.