Staged all over Los Angeles, Larry Clark’s “Wassup Rockers” follows the exploits of the Velasquez brothers (Jonathan, Eddie and Milton) and their pals Kiko and Porky (Francisco Pedrasa and Yunior Usualdo Panameno), Salvadorean émigrés who have rejected hip-hop culture in favor of refashioned old-school punk. Though not exactly a story of rebellion, the movie reveals kids engaged in their own version of an outsider movement, even if it takes place in an insider world.

Here’s the way one of the skateboarder kids in the movie explains the title: Other barrio kids don’t get the music, or the look, so it’s the second word that gets the derogatory emphasis, as in “Wassup, rockers?”

If you doubt that this simple act of disdain has within it the weight of an entire movie, you’ve forgotten what it’s like to be 15. The movie is happy to explain. Jonathan and his brothers wake for school, squeeze into the poster tubes they call pants and skate down to school, through their own neighborhood (“the ghetto,” as they humorously refer to it) and to Beverly Hills and back, through the backyards of celebrities and over the sketchy concrete of Hollywood. The boys talk sex, get hassled by cops, try to make it with privileged chicks, find themselves at a weird art party and get shot at by a kooky celebrity who looks alarmingly like Clint Eastwood.

“Wassup Rockers” captures Los Angeles in a ground-level, realistic light that few filmmakers have recently been able to do. The movie is a kind of fable of the poor, an urban picaresque, or maybe an urban Latino “Odyssey,” complete with fantastic creatures and daring escapes. The film has a rare vitality, something of the right-here-and-now that is an achievement likely based in part on Clark’s decision to cast the very kids who inspired him. He doesn’t even change their names. This is loose, unconventional filmmaking, and all the more fun because of it. (R) (111 mins.) **** S