Given that country music so routinely crosses into self-parody, a This Is Spinal Tap-style mockumentary on the rise and fall of a silver-buckled doofus in Music City would seem like a dim comic prospect, especially in the looming shadow of Robert Altman's Nashville. Though Dill Scallion fires too many obvious shots at line-dancing culture, trailer-park yokels, and other fat targets, former stand-up comic Jordan Brady's rambling debut is acquitted by generous, cheerfully offbeat wit and a charismatic lead performance by Billy Burke. As a slow-witted schoolbus driver turned country superstar from Muleshoe, Texas (proud home of Lee Horsley), Burke makes a winning foil, absorbing all the cheap barbs thrown at his character without tipping his ten-gallon hat. On the strength of "You Shared You," a honky-tonk ode to unfaithful ex-fiancée Kathy Griffin, and his signature Scallion Shuffle, a dance that requires him to shatter the bones in his foot, Burke and his band become an overnight Nashville sensation. Despite the efforts of hitmaking producer Henry Winkler, country music's answer to Phil Spector and creator of the "barn of sound," his fame proves fleeting, withering under the influence of Yoko Ono-like meddler Lauren Graham. Dill Scallion is smattered with amusing celebrity cameos, including a fine turn by the surprising Jason Priestley, but once the irony of its title character's unlikely ascent wears off, the film sputters along on good will alone. Like his affable hero, Brady can only go so far crooning the same tune.