Maybe you’ve seen them in your neighborhood: Dozens, sometimes hundreds of Santas ho, ho, ho-ing in and out of bars, stopping traffic and posing for photos. The red-suited, white-bearded revelers have gathered in Trafalgar Square in London and Tiananmen Square in Beijing. They’ve walked across the Brooklyn Bridge. And this past weekend in Los Angeles, they visited the space shuttle en masse at the California Science Center.

This weekend, the SantaCons schedule includes Benicia, Yountville, San Francisco, Santa Cruz and Sacramento.

“It’s innocent fun,” said Tim Mambort, 27, who’s been taking part in SantaCon in New York City for five years with friends from college. “You end up standing in a bar singing ‘Jingle Bells’ with people you just met, all dressed like Santa, or walking with hundreds of Santas to Central Park, or filling up an entire subway car with Santas.”

But whether SantaCon is naughty or nice depends on whom you ask.

The website for the New York City event, planned for Dec. 15, says SantaCon ”is not a bar crawl. Every time you call it that, a sugarplum fairy dies.”

But the fact is, most SantaCons involve stops at bars along a prescribed route, and over the years, there have been isolated reports of misbehavior. In New York, police have issued summonses for violations of open container laws, and some bars refuse entry to anyone dressed in red. Last year, residents of Lower Manhattan complained of drunken Santas vomiting and urinating in the streets.

“There was one Santa lying on the ground and I saw a father go by with two young children and the little girl said, ‘Daddy, what is wrong with Santa?’ ” said Community Board 1 member Paul Hovitz, who worries that the event encourages binge drinking and underage drinking.

Ian Sibley, who organizes the SantaCon.info webpage, acknowledges that “a dark shadow seems to haunt the event. So we take the extra step of emphasizing not drinking too much and perhaps supporting a good cause.”

Indeed, many SantaCons require participants to bring donations for food banks or Toys for Tots, or raise money for children’s charities or no-kill pet shelters.

Sibley started SantaCon.info five years ago with a half-dozen listings after “encountering this crazy thing with all these people dressed up like Santa” in Asheville, N.C. The website now lists nearly 275 events in 37 countries between November and January. Sibley says SantaCons have been held on every continent – from Uganda to Katmandu to Sydney and even Antarctica – but he dates the first events to the 1990s in Copenhagen and San Francisco. He says New York is one of the biggest, drawing 20,000 Santas.

Anna Sandler, a mom from Maplewood, N.J., thinks most participants take seriously the notion that SantaCon must not hurt Santa’s image. Two years ago while pushing her toddler in a stroller in Manhattan, Sandler encountered “tons of Santas crossing the street and had no idea why. It was the most amazing spectacle.” She stopped a few Santas to chat, then went home and looked the event up online.

“The Santas were completely hammered, but also completely polite,” she said. “They were definitely following the SantaCon creed of being super-respectful.”

Like zombie walks at Halloween, SantaCon is a grassroots phenomenon, organized locally and mostly through digital media, from email blasts and websites to Twitter and FourSquare. The term SantaCon may bring to mind Comic-Con, the pop culture convention, but there’s no industry behind SantaCon, though a growth in sales of Santa suits led Party City to start advertising on SantaCon.info in 2011.

“Our Santa suits have always sold to the Santa who dresses up at the mall or dad dressing up at home,” said Melissa Sprich, Party City’s vice president of costumes and accessories. “But we started to see an increase in sales and were hearing that local events were occurring with people dressing up for this SantaCon thing.”

Demographics for the events also led Party City to add Santa styles for women – including some sexy looks – as well as accessories like antlers.

Dana Humphrey, 29, who dressed like Mrs. Claus last year and is going as an elf this year, has made SantaCon in Manhattan a tradition with friends, starting with brunch, then joining SantaCon crowds for the route’s first stop at a bar in the Wall Street area. Along the way, they’ve posed for photos at the famous Wall Street bull sculpture and done an Ace of Bass singalong with 80 Santas.

“You’ll find groups of Santas doing all kinds of ridiculous things,” she said.

Nigel Parry is organizing the fifth annual SantaCon in Lowertown, an artsy historic neighborhood in St. Paul, Minn. The gathering drew 200 Santas last year and is accompanied by a brass band that leads revelers in and out of bars. One of the first stops is billed as an “all ages” event at the Black Dog Cafe where parents can bring kids. But how do you explain to a wide-eyed 5-year-old why there are 50 Santas, not just one?

“That’s up to the parents to get creative,” Parry said. “Some just say, ‘These are not real Santas – they’re just dressed up as Santa.’”

Some customers “come in early and stake out their seats” just to watch, said Sara Remke, co-owner of the Black Dog Cafe. “It’s very much a spectator event.”

But most SantaCons stress that they are not for kids, and Sibley says that’s part of the appeal.

“The holidays tend to be family oriented and adults get squat,” Sibley said. “They work hard all year and extra hard over the holidays. So when you get a costume on like Santa, the pressures of the real world are lifted. You have this strange camaraderie because everyone is dressed like you.”