Two punks, dressed in black, get on a plane. They are famous, as punks go. They make a very nice living at what they do. But when they have to fly somewhere to do it, they tend to fly coach, and they tend to fly Southwest Airlines, which offers nothing but coach. It's tempting to read larger implications into their preference for this most egalitarian of carriers-things about punk principle, about working-class sympathies, about a desire to breathe the same recycled air as everybody else who needs to get to Utah on a Friday afternoon. But we won't. Two punks get on a plane, and it happens to be a Southwest plane because Southwest flies out of Oakland, California, which is close to where they live.

The captain has turned off the fasten-seat-belts sign, and the middle-aged woman next to me asks if the man sitting across the aisle is a musician. The man in question is wearing a black suit jacket, a black T-shirt that reads Oakland in Olde English lettering, black pants, and a studded belt. His hair is dyed the color of squid ink and twisted into gluey spikes; the faded tattoo on his left hand spells out p-u-n-x. He is probably not a tax attorney.

The woman's eyes light up when I tell her it's Billie Joe Armstrong, singer/guitarist for Green Day. She knows Green Day, or at least she knows her daughter-a five-foot-11 distance runner who goes to school in Utah-likes Green Day. She knew they were musicians the minute they boarded, Armstrong and his traveling companion, Green Day bassist Mike Dirnt, a gangly guy with bottle-blond hair, now seated a few rows up. Armstrong reminded her of Elvis Costello; Dirnt was working "more of a Billy Idol thing."

A couple of years ago, the woman's husband, a commercial airline pilot, had the Backstreet Boys as passengers. They bought every seat in the first-class cabin, waited until the last minute to board, then pulled the curtain so nobody could bug them. This is better. The distance runner's mom asks if I think it would be okay with the man across the aisle if she asked him for an autograph for her daughter. I'm in no position to speak for him-I'm here to follow his band around for a few days, watch what happens, and draw some conclusions-but I tell her I'm sure it wouldn't be a problem.

If it is, Armstrong is gracious about it. He says, "Sure," and double-checks the spelling of her daughter's name-V-e-r-a-and in a second she's back in her seat with a piece of paper that reads, "Vera Billie Joe Green Day 04." At this point Vera's mom becomes curious about Green Day. They've been around for a while, I tell her. Seven albums. They're well-respected. Sort of elder statesmen in their field.

"Elder statesmen?"

Vera's mom takes another look at Armstrong. He's flipping through the SkyMall catalog (pricing humidors, maybe, or cognac?), one leg extended in the aisle, Conversed foot bobbing, a length of red-and-black striped sock exposed.

"Really?" Vera's mom says. "He looks so young."

"What did you call us? Elder statesmen?" Armstrong will ask when we land, sounding both surprised and amused. Armstrong and Dirnt are both 32; Green Day drummer Tré Cool is 31. They are hardly old. But they've been young for a long time. They were young when they made their first two albums for the Berkeley punk label Lookout!. They were young when they signed to Warner Brothers' Reprise Records, young when Kurt Cobain killed himself, young when music-industry executives and people at MTV, angling to fill the Cobain-shaped hole in their marketing plan, decided to push "Longview"-a song about a bored teenager on a couch, trying and failing (with pot, masturbation, television) to make a summer afternoon go by faster. A song they'd written as bored teenagers yawning through interminable summer afternoons of their own.

They were young when that song-with its odd, foot-dragging dynamics, its exuberant power-chord tantrums-caught the attention of bored teenagers across America. Young when their major-label debut, 1994's Dookie, went platinum, eventually selling ten million copies. Young as they made more records-good ones-and lived down the charge that their success constituted a betrayal of the scrappy, deeply doctrinaire underground-punk scene that had birthed them. Young that night in 1998 when Armstrong called his manager, freaking out, as St. Louis Cardinal Mark McGwire, who'd just broken a home-run record, ran a victory lap inside Busch Stadium while Green Day's "Good Riddance (Time of Your Life)," a lump-throated acoustic ballad off their 1997 album Nimrod, blasted from the P.A.

All three members of Green Day have been married. Armstrong's been with his wife, Adrienne, with whom he co-owns a small indie label, Adeline Records, for ten years, and has two sons. Two members have been divorced: Cool twice; Dirnt once, recently.

But while they've spent a decade dealing with increasingly grown-up concerns, they remain as viable a commodity as ever among discerning consumers of that which is young, loud, and snotty. "American Idiot," the title track and first single from their seventh and latest album, is a radio hit. According to Phil Costello, senior vice-president of promotion at Reprise, radio programmers responded to the record with a degree of enthusiasm unheard-of for a band that scored its first hits ten years ago. "I have nothing to compare it to," he says. "This never, ever happens." And on Green Day's current tour, longtime fans will have to fight for space in the mosh pit with 14-year-old newcomers-kids who got into the band via the countless other punk outfits who've learned from Dookie's example, kids who were in Barney the dinosaur's core demographic in 1994.

Cool sums up this peculiar state of affairs by paraphrasing Wooderson, the post-high-school lech Matthew McConaughey played in the stoner classic Dazed and Confused. "We get older," he says, "and our audience stays the same age."

But if, along the way, they've also become mature-"I hate that word," Armstrong says-it's a condition that's crept up on them, something else to rebel against.

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