A group of screaming runners makes its way through the streets of South Beach. Restaurant patrons look up from their meals with startled expressions. One runner blows on a conch shell.

Others chant, "On, On!"

At the halfway mark in the five-mile run they stop at a bar called Lost Weekends to hydrate themselves — with beer.

These are the Hash House Harriers — not runners with a drinking problem, but drinkers with a running problem. Or so they say.

Once a week, the hashers partake in a run that is equal parts scavenger hunt, pub crawl and social gathering.

"I love it," said Rich Aube, a 35-year-old real estate agent from Dania Beach who has been hashing for four months. "I like to run and I don't mind drinking."

The Miami-Fort Lauderdale chapter has about 300 registered members, a group that includes a National Hurricane Center meteorologist, a Broward County School Board member, a journalist, Navy officers and a dog. They range in age from 21 to 58. Most are men.

It's similar to Hares and Hounds, the British children's game whose rules call for one member of the group (the hare) to run ahead of the others (the hounds) and leave behind an intricate trail marked with flour.

The hash started more than 70 years ago by Army officers living in Kuala Lumpur, the capital of Malaysia.

After their morning run, they would end up at the Hash House bar.

For the modern-day hashers, either a pub or a beer-stocked cooler awaits the end of the run.

Through expatriate communities around the world and those who love knocking back a beer or two, running and a dirty joke, the ritual has evolved into an intricate society complete with a Bible, an anthem and Web sites like www.gthhh.com. There are 1,834 chapters registered in their online directory, in 178 countries and every American city. There are even chapters in Antarctica.

"That's the best thing about the hash," said Nick Hogan, 38, an accountant from Fort Lauderdale, one of 24 people (and one dog) running in Miami Beach. "If you do a lot of traveling, you can always look up a hash. They'll bring you in like family."

Although there is no formal headquarters or rules for the hash, there are hashing conferences, like the worldwide Interhash, held every two years in a different city. Similar to the Olympics, hashing chapters in each city lobby for the chance to host the festivities. More than 6,000 people attended the 2006 Interhash in Chiang Mai, Thailand. The next one will be in 2008 in Perth, Australia.

There are also themed hashes: the red-dress run, where everyone wears a dress.

Then there are steadfast traditions: A donation of a few dollars is given upfront. If you wear new shoes to a hash, you'll be forced to drink out of them.

After a hash, first-timers are heckled into singing a song, flashing a covered body part or telling a joke, preferably dirty. And everyone has a hash name.

"Your name is somehow related to you in some way. Either your profession or a personality quirk or something goofy you do while you're drinking," said Marion "Liquor Briefs" Lohmayer, 43, a bartender turned paralegal.

Lohmayer regularly hashes with her dog, a boxer named Frankenstein, and her husband, whom she met while hashing.

Hashers only address each other by their hash names.

"And if you don't like a name, they'll give you a worse name," she said.

There is, as with any subculture, hasher lore.

Pedestrians and police often ask the group what they're doing.

After the terrorist attacks of 9/11, authorities thought the flour the hashers threw on the sidewalks to mark their trail might be anthrax. After several run-ins, they temporarily turned to chalk and toilet paper.

Most hashers are men in their late 30s and early 40s, but there are hashes on college campuses, senior hashes, hashes on military bases, hashes for children (they drink soda), for swingers, for women — the list goes on.

The local chapter, started in 1989, is a traditional hash.

Each hash has its own characteristics geared to the area. In cities where snow falls, hashers drop Jell-O into the snow to mark the trail.

In South Florida, hashes have taken them into boats, through the swamps of the Everglades and on a recent Monday, through the Art Deco streets of Miami Beach.

That particular hash began and ended in a parking lot, where they stretched their limbs, chugged some beers and sang bawdy songs — along with chatting about their mortgage payments, jobs and children.

"Some of us are marathon runners," said Michael Tichacek, 43, a National Hurricane Center meteorologist from Miami.

"Some of us are beer drinkers. But the best part is nobody wins or loses. You just show up."