Real sounds of a phony

According to John C. Reilly, star of the music-film parody "Walk Hard: The Dewey Cox Story," opening Friday, the typical rock musician finds his sound early on in his career, then sticks to it for the rest of his life. He might make minor adjustments to keep up with the times, but his devotion to a tightly defined artistic persona never wavers.

Dewey Cox, on the other hand, knows no such stylistic loyalty. Reilly's fictional rock-star alter ego in "Walk Hard," Cox "totally reinvents himself every five years," Reilly said backstage at the Roxy in West Hollywood recently before he and a five-piece band took the stage for an hourlong performance as Dewey Cox and the Hard Walkers.

That shape-shifting quality -- the ability to go from a small-town rockabilly dude to a track-suited disco maven -- is what makes Cox unique, Reilly said. "He's kind of like the Forrest Gump of music."

That could be it. Or maybe it's Cox's obsession with his nipples.

"You've seen the billboards," Reilly-as-Cox bellowed halfway through the Roxy show, referring to the "Walk Hard" ads presenting Reilly in a topless rock-shaman pose a la Jim Morrison. "Now see the real thing!" And with that he ripped open his mariachi shirt and zestily caressed what the audience of chuckling industry insiders could behold only from afar.

Columbia Pictures has Reilly on the road baring his chest through tonight, when he's scheduled to perform with the Hard Walkers at New York's Knitting Factory. (In addition to L.A. and New York, the tour also touched down in Cleveland, Chicago, Nashville, San Francisco and Austin, Texas.)

Valerie Van Galder, the Sony division's president of domestic marketing, says the Cox trek is part of a "Walk Hard" marketing campaign built around an emphasis on Reilly's character. She compares it to the push behind last year's NASCAR spoof "Talladega Nights: The Ballad of Ricky Bobby," in which the film's star, Will Ferrell, made the racing-event rounds as his character.

"We're trying to do fun, clever things about Dewey Cox's place as a rock 'n' roll legend," Van Galder says. Among them: a series of VH1 and YouTube spots featuring real-life rock stars such as Sheryl Crow and John Mayer discussing Cox's influence, as well as the so-called Cox Box, a lavish promotional set housing items that include a piece on the mock rocker's life and times by Rolling Stone writer and editor David Wild.