(FORTUNE Magazine) – Take it from us: If you can't pronounce "JNCO," you're hopelessly out of touch. JNCO is the name in jeans for teenage boys, the brand that launched seriously wide-leg pants. JNCOs are so wide they swing like a double-barreled hoop skirt and drag along the pavement, collecting chewed gum and other sidewalk scum. Don't laugh: When Teenage Research Unlimited recently asked teens to name the "coolest brand," JNCO came out sixth, right behind Tommy Hilfiger and Adidas among boys ages 12 to 15.

Nicholas Lynch, an 18-year-old from the Bronx, owns 11 pairs of JNCOs. One recent afternoon, Lynch sashayed through the subway in JNCO Mammoths with leg openings 40 inches wide and pockets 17 inches deep. (Your basic Levi's 501s run about 16 inches wide, with six-inch pockets.) Lynch concedes his JNCOs are "a bit of a pain" (people step on them), but he wouldn't wear anything else. Even his formal wear is JNCO: When he goes to church or to a sweet 16, he slips on JNCO khakis. "They look just like Dockers," Lynch insists. "Just bigger."

Brand loyalty like that is hard to come by. In the teen market, what counts, it seems, is giving the impression that you're a funky little underground operation, even if you're not. Brothers Haim and Yaakov Revah, owners of Revatex, the Los Angeles firm that makes JNCOs, understand this game. To preserve JNCO's cool factor, Haim (he goes by "Milo"), 39, and Yaakov (a.k.a. "Jacques"), 34, refuse to talk to the press. After all, if FORTUNE knows how to pronounce JNCO, so will mom and dad. In teenland, that's the kiss of death.

The Revahs have a lot to lose. Last year, according to Tactical Retail Monitor, a New York market report, the U.S. market for men's jeans grew 5.9% to $6.3 billion, while the market for wide-leg jeans alone grew 30% to $900 million. Revatex is privately held and won't reveal sales, but big retail customers estimate its wholesale revenues at well over $100 million and maybe as high as $200 million. This is no little shop.

Of course, teens see only JNCO's quirky subversive face, which is reinforced by ads in magazines, like Electric Ink and Thrasher, that target cool young (mainly white) men who are into skateboarding, extreme Rollerblading, and raves, those all-night techno dance parties. Revatex quietly "flows" free clothes to trendsetters. Big-name DJs in the rave scene are outfitted by JNCO, as are members of edgy bands like Limp Bizkit. The company also sponsors extreme athletes like BMX biker Todd "Wild Man" Lyons and Sean Mallard, king of street luge, a psychotic form of skateboarding that's done lying on one's back--at 70 miles per hour.

JNCO's way-cool image has been a painful blow to Levi Strauss, brand of choice among the no longer cool (read "baby-boomers"). As Nicholas Lynch--he of the 11 pairs of JNCOs--puts it, "Levi's came out with wide jeans, but it just isn't the same because of who wears them." Translation: Losers wear Levi's; hipsters wear JNCOs.

The Revah brothers are nothing if not pragmatic. Hipsters may give a brand the right image, but to make it big, you need the masses. So while the brothers publicly hype their "image accounts," including stores like Ron Jon Surf Shops, their main customers are downright pedestrian: J.C. Penney (where JNCO is the No. 1 brand among young men) and Pacific Sunwear, a mall chain with 273 stores.

Such a sober approach to business may just save JNCO from dying the death of a thousand trendy brands that came before them--once-hot names like Mossimo and Cross Colours. Already, Revatex has branched out into JNCOs for teen girls, JNCO shoes, and JNCO tops. JNCO backpacks are in the works. The clearest sign of the Revahs' survival instinct is their new Funky Basics line, classic jeans almost as dull as Levi's. J.C. Penney says the line is selling fast.

A footnote: FORTUNE wasn't allowed to meet the Revahs, but we were curious--do the brothers wear JNCO jeans? "I can't even entertain that question!" exclaimed their lawyer. "Look, you're killing me here. I mean, I don't want to disenfranchise them from their customers." We'll take that as a no.

As for pronouncing the company's name, you'd better ask a teenager.

--Nina Munk