Trashy chic is an increasingly popular — and scary — trend in Hollywood nowadays. Amongst the younger set, unshaven stars hang out in dives, lookin' dingy in vintage T-shirts and trucker caps. Witness Glamour's annual "Glamour Don't" party, where the beauty mag's A-list guests — including Tara Reid and Owen Wilson — are urged to show up in mismatched, over-the-top getups. Sure, it's all in fun. But how to tell whose fashion faux pas are intentional, and who's just trendy?

Lance Bass, for one, looked fairly normal, with his spiky blonde highlights and yellow U.S. Army T-shirt. "My fashion don't is wearing a brown belt with black shoes," he told Party Boy, grinning. "I wanted to go further, but my publicist wouldn't let me."

Actually, many celebs wimped out for fear of spoiling their photo ops. Bruce Willis and Yoko Ono both opted for a black leather jackets. Shane West — who stars in A League of Extraordinary Gentleman this summer — also erred on the cool side: "Sunglasses at night is very Miami Vice," he smiled. And two of my fave WB kids — Everwood's Gregory Smith and his date, 7th Heaven's Ashlee Simpson — came casually sporty.

Perhaps they figured just coming to the party was enough of a "don't"? This shindig's unfashionable L.A. address — the Shakey's Pizza on the corner of Santa Monica and Orange — is a well-known haunt for, shall we say, women of the night. And some of 'em ain't even real women.

"I didn't wear a glamour don't tonight," said Olympic skater Tara Lipinski, who ironically plays an ex-hooker herself on 7th Heaven. "I just came to see glamour don'ts. Some guy was mooning the entire press line! I think that qualifies."

The cheeky fellow in question was Popular alum Ron Lester, who played the plus-sized Sugar Daddy on WB's late, lamented comedy. So proud was he of losing nearly 300 lbs. — yes, you read that right — he felt moved to tip his cowboy hat to paparazzi, then flash his bottom at 'em! If only Party Boy's Glamour gift bag contained smelling salts, to stave off a case of the vapors.