The two twentysomething ad guys tinkered with slogans that might shorthand a new Vegas — not the purportedly family-friendly resort destination of the 1990s but the new old Vegas, the silicone-and-keno Sodom and Gomorrah of the 21st century.

None of it quite worked: "Las Vegas: You know how it goes." "Vegas: Keep it between us." "Las Vegas: Get in on the secret."

And then, lightning. Brilliant, wicked lightning.

Working apart, Hoff and Candido both came up with variations on a five-word phrase uttered sotto voce by long-ago traveling salesmen and sailors on shore leave: "What happens here, stays here."

"We liked it because it introduced a tiny truth, one that everyone knew but hadn't been publicized," Hoff says. "We felt the truth was the way to go."

You probably know where the story goes from here. "What happens here" has since transcended its status as a memorable advertising line to become a bona-fide pop-culture touchstone, the "Where's the beef?" of its time. Billy Crystal riffed on it during the Oscar telecast, as did characters on "Frasier" and "The Simpsons." Laura Bush (of all people) invoked it twice to winning comic effect on "The Tonight Show." Former morals czar and enthusiastic gambler Bill Bennett lamented to Jay Leno about televised footage of him playing the slots at a casino: "Apparently, 'What happens here, stays here' applies to everyone but me."

In advertising parlance, the ad campaign accompanying the slogan has "repositioned" Las Vegas as the Sin City it has always been since its mobster founding.

It does so via a series of "Vegas Stories," 30-second vignettes that play off consumer research suggesting that people imagine Vegas as a place that is "commitment-free, pressure-free, judgment-free," according to Billy Vassiliadis, chief executive of R&R Partners, the Vegas ad agency that created the campaign.

So one ad shows a wildly dressed young woman flirting with her limo driver on the way to the airport; upon arrival, she emerges conservatively dressed and businesslike, ready for her return to the real world. Another features a young man who asks the Vegas hotel desk if he can get a wake-up call transferred to his cell phone since he's not sure where he'll be when he wakes up. (The sexual ambiguity of the lead character won plaudits from gay viewers.) Others focus on mischievous senior citizens and an impulsive bride.

The latest commercial, a kind of victory lap for the entire campaign, shows many of these same characters on a plane leaving town; their varied expressions suggest the tales they'll tell back in Palookaville.

"What we've tried to show is the precursor, and the aftermath, to a personal story, and let viewers fill in the details," says Candido, who, like Hoff, has since moved on to a bigger agency. "They're successful because people can imagine more than what we show. A grandmother who sees these spots can imagine that (the debauchery) is spending too much time at the buffet. The 23-year-old bachelor party guys can have their own ideas about what went on."

Says Vassiliadis: "People always ask if the spots are about sex. If that's what you want to read into it, that's fine."

Indeed, the ads occupy a kind of noncontext, an Anywhere of diners and limos and hotel lobbies. There are hardly any of the usual signifiers of Las Vegas — no flashing neon, no showgirls and no gambling. Instead, what ad agency creative director Randy Snow has imagined is a certain thrillingly dangerous but slightly seamy psychological atmosphere.

Not everyone is thrilled, of course. The campaign has been criticized by the Nevada PTA and religious and civic groups who have questioned its implicit tawdriness.