If, by any chance, you'd like to see an illustration of the fickle nature of pop fame even more sobering than the career of Right Said Fred, then check out Stoked: The Rise and Fall of Gator. In the early 1980s, Mark Rogowski was a street jock with an eager, rakish grin. At 17, nicknamed Gator, he became one of the breakout icons of the newly visible and commercialized skateboard scene. He starred in videos, and he got to be a pitchman for Vision Street Wear, hawking boards derived from his own designs. He also performed for crowds of adoring fans, thrashing his board up into the air in the ''vert'' style that had originally put skateboarding on the map as a pioneer extreme sport. And then? Then, with startling suddenness, the vert technique, for all its daredevil virtuosity, became passé. It was as if Michael Jordan had been told, back in, say, 1989, that he might just as well stop all that flying and dunking stuff.
Had ''Boogie Nights'' been the tale of a California dreamer with a really long skateboard, the movie's delirious first half would have been ''Dogtown and Z-Boys,'' and its downbeat conclusion would be ''Stoked.'' It's fascinating to see the process by which skateboarding, in all its concrete grittiness, was transformed into a mainstream activity of consumer cool. The packaging went only so far, though. For a while, Gator glories in his role, rubbing shoulders with ''Downtown'' Julie Brown on ''Club MTV,'' but he becomes so tied in to merchandising that he loses his street cred, and the skateboard kids reject him. ''Stoked'' turns into the story of a deeply disturbed young man who lashes out in violence. Yet the last part of the movie could almost be any tabloid-TV profile of a killer next door. It's the dark side of one random, troubled soul passing itself off as the dark side of skateboarding -- a sport that, precisely because of the media savvy of athletes like Gator, may no longer be much of a breeding ground for danger.