The floor of Garry Wang's office is strewn with entertainment magazines, a change of clothes, toy pistols, a severed stuffed arm, plastic balls, soda cans, pens, books, videotapes and piles and piles of paperwork. It keeps him organized: If he steps on something, he won't forget it.

The company he founded, online entertainment news site Synge.com -- www.synge.com, is expanding, and Wang is excited. "We're calling the new room Area 51. It'll have video games, television and loud music," he says. In other words, today's typical business environment.

"The corporate mainstream is less appealing to this generation," says Wang, who is 30. "For guys my age, the office is an extension of the college dorm."

And for guys his age, this is coming of age. Where once childhood's end meant giving up toys and donning a suit, successive generations are increasingly doing neither. See that guy in a T-shirt and shorts skateboarding down the street on his way to play video games? Chances are, he's 29.

"A lot of kids today say, `I can wait to be an adult,' " says Gene Del Vecchio, who runs a retail consulting company called CoolWorks. "They don't want to grow up all that fast."

Or they're changing what being "grown-up" means. Microsoft and Yahoo! have popularized the tieless office, while President Clinton's White House has been infamously littered with empty pizza boxes and diet Coke cans. The average age of someone playing a Nintendo video game has jumped from 14 to 18 during this decade, according to the company, and the average player is 20 at competitor Sony Entertainment.

Rock concerts, surfboards, Beanie Babies, comic books -- they're not just for kids anymore. The line between maturity and childhood has blurred, or vanished completely.

"There was a stigma when I was younger about cartoons," says Linda Simensky, who is 35. "To show that she was grown-up, a girl would start watching dramas. It was a way of proclaiming that you were older."

Now, as vice president of original programming for the Cartoon Network, Simensky is pleased to note that 30 percent of her channel's audience is over age 18. On any given day, 182,000 people between 18 and 49 watch Cartoon Network, which is more than watch either VH-1 or CNN.

There is no rite of passage in pop culture anymore, Simensky says. "The X-Files" mingles with "The Brady Bunch," and cartoons with medical dramas. Starting with the baby boomers and continuing with the aging of Generation X, the demographic for "kid's stuff" is ballooning by decades.

"It's happening on both ends -- people are older at a younger age and younger at an older age," Simensky says. "These days, it's more acceptable to become a teenager when you turn 9, and remain a teenager until you're 29."

Nowhere is this more true than at a stereotypical Internet start-up, of which Synge.com of Costa Mesa, Calif., is one.

Buried within an unremarkable gray office park, Synge.com's crew works in cubicles crammed with movie posters and compact discs. Here, where job titles range from "research vixen" to "task master," the dress code is lax, the hours long. As Wang explains, as long as the work gets done, the atmosphere should be relaxed.

Synge.com manages a Web site that delivers entertainment, news and sex advice to 18- to 49-year-olds. The attitude is cynical, sly, but most of all lighthearted, says Becky Firth, the editor. It's a perspective, she adds, that values creativity over tradition.

"I like to think that we're not sarcastic for the hell of it," Firth, 29, says. "I'd say we want the more honest reaction. No pretense."

That whimsy carries over into personal lives as well. Firth says she dates men who ride skateboards and play video games into their thirties. "As long as they're goal-oriented, if they're interested in that stuff, it's fine."

In a recent episode of the television show "Sex and the City," she adds, a character swooned over a "traditional" man who "loved routine." "I would go running," Firth says. "I'm not concerned about what's the `appropriate' thing to do."

As more people of her generation move into positions of influence, Firth believes this sort of disregard for tradition -- in both dress and activity -- will spread. "I hope it will continue on. It's a huge draw, being able to work like this -- it makes us work harder. We certainly don't want to give that up."

Though Firth and Wang say their parents and friends at first were taken aback by their work environment, the relatives are more jealous than disapproving, they said.

"The success of companies like Yahoo! and eBay legitimizes what everyone else is doing," Wang says. "Without those guys it would be difficult to explain our aesthetic to the outside world."

That aesthetic dates back even further, Del Vecchio says. Before Yahoo! there was Apple Computer, which thumbed its nose at the dark-suited world of IBM. Silicon Valley's corporate culture has had a greater influence on other industries as its dominance in the general economy has grown.

Apple's founder, Steve Jobs, was a classic baby boomer, Del Vecchio adds. "They grew up wearing blue jeans -- they didn't mind holding on to those things. Baby boomers never lost that kid mentality. The generation that was before them had lived through war; they were very, very serious."

Having lived through Vietnam and the cultural revolutions of the '60s, however, baby boomers had their share of upheavals. And they did retain many "adult" traditions: The corporate icon of the '80s, after all, was the power suit.

Generation X, though, has embraced the Peter Pan lifestyle with greater enthusiasm. The reason may be that Gen X was never touched by a serious social upheaval, or that the generation is simply less dull, depending on your point of view.

"As you look at how Generation X has grown up, there's a mentality of irreverence," says Charlie Bellfield, director of marketing communications for Sega, a company trying to sell video games to Gen X'ers. "It's sometimes referred to as laziness, or cynicism, but they're sophisticated."

They are, Bellfield adds, caught in a pop-culture feedback loop -- enjoying new input but relishing the old. That's why they buy Sega Dreamcast game systems but still like Pac-Man. They watch "The X-Files" but also "The A-Team."

"Cable television, which this generation grew up on, started out as a medium for reruns," Simensky says. On the Cartoon Network, twenty-somethings may tune in to get their "Scooby-Doo" fix but stay for new animated shows, she says.

Orion Tippens, an employee at Mile High Comics in Anaheim, credits the Internet for helping keep the trappings of '80s youth alive. "A huge part of this collecting trend is eBay. People go online and say, `I never realized there were so many people who liked what I liked,' " he says.

At the same time, children's items are becoming more sophisticated. Comic books have very adult themes, while cartoons appeal to older audiences, especially since the advent of "The Simpsons" a decade ago. While many of these genres appeal mainly to men, women are holding onto their youth as well, Simensky says.

"In Japan, the same thing is happening -- all these 30-year-old women are walking around with `Hello, Kitty' purses," she says. "It's a strange combination of nostalgia and fashion.

"It is easier to be a guy and be involved in the passions of youth forever," Simensky continues. "Girls are expected to grow up faster. But now women are doing it, too."

What's changed for both women and men is that society does not require them to mature as quickly. As teenagers, they aren't needed to help on the farm or run the family business. The average age for a first marriage today is 25 for women, 27 for men, compared with 22 and 24 two decades ago. People are waiting longer and longer to start families.

As Generation X starts to have children, meanwhile, there's nothing to say they won't continue to do childish things with their own kids, Del Vecchio says.

"We now live in a world where everyone has grown up on Disney," he says. "We love going to Disney films, we love going with our kids to Disney films. It has become ageless."

Which doesn't mean there aren't certain dangers to an extended childhood. Firth, for instance, hopes the business world holds onto certain dignities.

"You should still come to interview in a tie; I hope that wouldn't go away," she says. Firth adds that during a meeting with another Internet company, one employee made an off-color, sexual remark that caught her by surprise. "It was so casual, so lax there that it made me uncomfortable."

A sense of fun, she says, has to be balanced with a sense of purpose.

As David Cole, president of consumer research firm DFC Intelligence, says, "Sometimes the fact that more older guys are playing video games all the time causes problems with their girlfriends."

There's a question, meanwhile, as to whether Generation X and successive generations will carry their casualness into the next decade; whether, at age 40, Internet entrepreneurs still will conduct meetings from beanbag chairs and decompress with a football game on their Sony PlayStations.

Tony Cherbak, a retail analyst with Deloitte & Touche, thinks they will. "Anything that was popular for the baby boomers has resurfaced, and the same will happen for this generation," he says. "Right now, it's the adults who buy the sophisticated toys. You go to a slot car track, and a kid has one car. An adult comes with a 16-drawer fold-out case."

He notes that Quiksilver, the surfwear manufacturer, has a new line of clothes aimed at surfers over 35. Other companies are doing the same thing, Cherbak says. "The little boy never grows up -- he just gets more expensive toys."

It's forcing manufacturers and promoters to change their marketing strategies, Del Vecchio says. "What is happening is that companies are having to develop ideas that touch chords in multiple age groups -- all the better to retain customers," he says.

Del Vecchio adds that parents and their children will continue to get closer and closer in taste and style. Already, it's harder to shock older generations that grew up, first on the Rolling Stones, now on Nine Inch Nails.

"For companies, the mindset cannot be, `Let's go after children,' " he says. "It's `Let's go after the child in all of us.' "