By Barbara De Witt
Daily News Fashion Editor

Ever since "Melrose Place" star Alyssa Milano announced on "The Tonight Show With Jay Leno" that she wasn't wearing any underwear, folks have been buzzing about it. Or the lack of it.
     Was she the victim of a heartless panty-raid prank?
     Did she miss the lecture about wearing good underwear in case of a car accident?
     Did she take that jeans campaign - "Nothing comes between me and my Calvins" - seriously?
     And, more importantly, is the young actress' aversion to panties a singular incident, or part of a growing trend that's sure to insult the moral majority?
     Like maybe she'd seen "Basic Instinct" too many times. You know, the film in which Sharon Stone silences a room full of jaded cops by simply uncrossing her ladylike legs and exposing a whole lot more than Marilyn Monroe did in the "The Seven Year Itch."
     In case you're wondering, Stone doesn't wear underwear in her personal life, either. She's said so in numerous interviews.
     This obvious refusal to wear underwear can't be a retaliation to the high prices of lingerie, because underwear sales are up by 9 percent since last year, according to fashion trend watchers at Fairchild Strategic Information Services.
     Perhaps, it was just an attention-getter, suggests Susan Colman, president of Jezebel, a leading bra and panty maker. "I saw the show. It got my attention," she said with a chuckle, referring to Milano's revealing statement.
     Milano, like Stone, didn't actually expose any part of herself visually, that is. It was just the thought of a Hollywood star sans panties that got us all flustered.
Crossing a line?
     But they aren't the only ones who crossed the line on panty lines. Jay Leno also learned actress Tori Spelling doesn't wear underwear.
     And neither does "Baywatch" babe Donna D'Errico, who showed up for a recent fashion layout for the Daily News without panties or bra.
     And we thought Madonna was outrageous. At least we knew for a fact she wore underwear... even if it was worn as outerwear.
     So, what's the deal?
     "Comfort," says Shari Belafonte. "I rarely wear underwear... but I definitely wear panties with a short skirt," Harry's daughter said over dinner at the opening night gala for the Hollywood Bowl.
     Since everybody in the group was talking about the Jay Leno show (with Alyssa Milano), she mentioned that at least half of the stars walking down the red carpet on Oscar and Emmy night aren't wearing underwear, either.
     Former runway model Jane Mannfolk, who's now a stylist for "Leeza" (yes, Leeza wears underwear) and "Interior Motives" on the Discovery Channel, says the suspected trend really is a trend, and she thinks it started years ago with fashion models.
     According to Mannfolk, "Traditionally, European runway models don't weae underwear because designers don't want any lines showing under the garment. However, it's also for convenience, since models must change quickly into several ensembles during a show. But this isn't new. It's just that it's become more obvious due to the currently sheer and clingy clothing, so it's caught on with anybody who's proud of their figure."
     Bottom line?
     "It's sexy to say, 'I'm not wearing any underwear.' But just for the record, it's also very uncomfortable. Why someone would want to wear tight jeans without panties is beyond me," she said with a laugh.
Short substitutes
     While Mannfolk takes a liberal view on runway nudity, the stylist does get upset with the everyday housewives who have been selected for fashion makeovers on the "Leeza" show. Quite a few actually show up without underwear, so she keeps a supply of flesh-colored G-strings by Calvin Klein to protect the borrowed clothes - and the TV viewers.
     Now, about that G-string trend. Some think it started with Demi Moore in "Striptease," and others say it kicked off with the black G-string featuring the Gucci symbol. You may have seen it in magazine ads, worn as a swimsuit brief or exposed under a hip-riding skirt.
     Regardless, G-strings and their slightly more modest cousin - the thong - have become popular panty choices for women who don't like visible panty lines and no longer wear pantyhose.
     Even mainstream companies such as Jezebel make them, but before you start wondering what the world is coming to, read on. According to Colman, most women in America still buy modest white panties. She adds that her biggest seller is a "waist-high panty with a high-cut leg, a cotton liner and good coverage in the back."
     Going without underwear isn't a political statement like the bra-burning era of the '60s, nor is it a sexist remark. Guys do it, too.
     Comedian Rodney Dangerfield has been known to partake of undies-optional fashion... and an entire episode of "Seinfeld" had Kramer celebrating new-found freedom when he shed his shorts..
     And what about that video artist Nam June Paik? He stood up to greet President Clinton at a recent White House state dinner for South Korean President Kim Dae Jung, and his pants fell down to his ankles, revealing... "The Full Monty."
     Forget meeting the president. Let's do America a favor and introduce him to Joe Boxer.