It's considered rude, adolescent and low-class, but celebrities seem to have no shame about chomping on gum in public.

Britney Spears, Drew Barrymore, Sharon Osbourne and the "stars" of Joe Millionaire and The Bachelorette all seem to have very little compunction about chewing with their mouths open, even when the cameras are rolling.

"I saw it everywhere and thought it was gross and tacky," said New York Post editor Maureen Callahan, who recently featured a collage of celebrity chewers in the paper's Sunday section.

Callahan caught Barrymore gumming it up at the premiere of Confessions of a Dangerous Mind and Osbourne masticating during L.A.'s Fashion Week.

But Spears, whose wad of gum is as ubiquitous as her newsboy cap and bared navel, is the "worst offender," Callahan said.

"At The Recruit premiere with Colin Farrell, she wasn't even chewing with her mouth closed," she said.

The Louisiana lass has also been photographed blowing big blue bubbles and spitting an already-been-chewed gob out a car window.

Gum has hit the reality circuit, too. Viewers of Joe Millionaire saw competitors for Evan Marriott's heart chomping before on camera — not to mention smoking cigarettes and cursing.

And Bachelorette winner Ryan Sutter had no qualms about showing the world how he keeps his breath fresh for Trista Rehn. He chewed away on camera as he got ready for the couple's final TV date.

The trend could simply be due to the rising popularity of gum. Wrigley's spokesman Chris Perille said business in the U.S. has been "very positive" over the last couple of years.

"There has been more energy and activity in the past year or two," he said. "The growth rate in Wrigley's volume was 5 percent in 2001 and 9 percent in 2002. Roughly half the population chews gum on a regular basis."

Perille also asserted that gum's reputation for being tacky has changed over the past few generations. "People have grown up with it. They recognize the benefits and know the product can be used discreetly in a number of settings," he said.

These benefits include tooth-cleaning and whitening, breath-freshening, appetite-suppressing and tension-easing, Perille said.

Etiquette expert Lesley Carlin, co-author of Things You Need to Be Told: A Handbook for Polite Behavior in a Tacky, Rude World!, agreed that gum has become acceptable — as long as it's used quietly.

"It's OK if you can do it without attracting attention to yourself," she said.

In fact, it may even be hip to chew gum now — or so Wrigley's ads would like us to believe.

Orbit gum commercials are narrated by the attractive British spokesmodel "Vanessa," and have a "tongue-in-cheek, almost mod approach," Perille said. Big Red advertising targets the "social sirens," which Perille defines as club kids. And print ads for Eclipse gum feature the hip-hop saying "fa shizzle," which means "for sure."

"There's been a concerted effort to make sure ads are edgier, with more use of humor," Perille said.

Elycia Rubin, fashion director for E! network, said stars like Spears and Barrymore chew gum not carelessly but deliberately, to show they're "sassy and fun."

"They do it because they have a sense of humor and an edge," she said. "They're like your best girlfriend having fun."

But Callahan said she doesn't think most stars in sticky situations are even conscious of their bovine behavior.

"It's a thing that everybody does, but most people are not in a position to be constantly photographed," she said. "They forget they shouldn't be talking and chewing at the same time."

Carlin agreed that there are times and places for gum, but the red carpet is not one of them.

"Have an Altoid," she said.