Adam Moore once drove 500 miles just to eat a burrito at a Chipotle he'd never been to.

Alan Klein is working on a smartphone app to help fellow enthusiasts track down the transient McRib sandwich.

And Ben Skelton made an unusual choice for best man in his upcoming wedding: the Chick-fil-A cow.

"I've already told my best man that he's going to be my second-string best man," said Skelton, a 28-year-old chaplain's assistant in the Air National Guard. "I just haven't told him that he got beat out by a cow."

Call it fanaticism or simply dedication, but these are the type of ultra-enthusiastic fans that every restaurant craves. Restaurant groupies have always been around, but they're more valuable at a time when the economy is forcing consumers to choose carefully when they eat out, and a few online posts can inform the opinions of thousands. While there are no known statistics on these fanatics or even agreement on who qualifies as one, restaurant chains realize that influencing a few hyper-excited fans with free food and T-shirts can sometimes be more effective — and much cheaper — than a big advertising campaign.

"You really can't buy publicity like that," said Chris Arnold, spokesman for Chipotle Mexican Grill Inc., referring affectionately to "lunatic customers" who do things like dress up as burritos to score free meals at the Colorado-based chain. He adds that the company tries to cultivate "loyalty and, in extreme cases, even evangelism."

Fast food has indeed become the gospel for many. About 23 percent of Americans eat fast food at least 20 times a month, according to Jeff Davis at Sandelman & Associates, and another 20 percent indulge 12 to 19 times a month. But few restaurants inspire cult-like dedication. Those that do usually offer only one or two main products, or they're able to create an aura of scarcity.

That's why the ubiquitous McDonald's usually sells its pork sandwich, the McRib, in only a few markets at a time. Last year, when McDonald's briefly made the McRib available at all U.S. locations, it said that the "obscure availability," as well as the barbecue sauce, led customers "to perform extraordinary feats" for a taste of the sandwich. McDonald's Corp. said the McRib helped fuel November sales, but declined to give details.

Perhaps no one knows that better than Alan Klein, a 29-year-old meteorologist in the Minneapolis area. He'd never go out of his way for a Big Mac, which are hawked at every McDonald's. But he loves the McRib because it's hard to get. He even created a website, the McRib Locator, so fellow fans could report sightings.

"That's the whole lure of it," said Klein, whose enthusiasm for the pork sandwich started when he was a child, growing up in a hog-raising family. "If it's around, you never know when it's coming back."

His website is a labor of love that's hard to police. For accuracy's sake, check marks indicate that someone has sent a receipt proving their McRib purchase. But, Klein warns on the website, "Please call ahead to confirm the McRib is available before traveling any great length to purchase one."

According to the McRib Locator, the sandwich is currently being sold in parts of Canada, but Klein doesn't have a passport. "If someone's making a trip across the border, we'd definitely be interested in them bringing us one," said Klein, whose wife, Kimberly, is also a fan.

Some restaurant groupies are willing to go great lengths for the object of their affection. Take Moore, the Chipotle fan. He got the idea to visit all 71 restaurants in Colorado while eating lunch with his sister at, naturally, Chipotle.

It took almost three years. By the end, Moore had logged 3,839 miles on his 1987 BMW and spent $528 on burrito bowls.

"There would be periods of lethargy," he said, "and then periods of 'OK, let's get this done.'"

Moore, 25, divides his time between Denver and Lake Placid, N.Y., where he is training to try out for the 2014 Olympic skeleton team. He had hoped Chipotle would let him eat lunch with founder Steve Ells when he completed his quest, but the restaurant sent the head of customer relations instead.

"Steve's schedule is very, very busy and as much as he loves to meet great customers, he has many demands on his time," said Arnold, the Chipotle spokesman.

Chick-fil-A, an Atlanta-based chain with a big presence in the South, has a whole rulebook for how to reward super fans.

Whenever it opens a new restaurant, the first 100 customers get 52 coupons for free meals. Fans usually have to be in line 24 hours in advance to make the cut __ and sometimes even that's not enough.

The restaurant turns the overnight wait into a party in the parking lot, with hula hoop contests, karaoke, and lots of free chicken. It does line checks to make sure people don't leave, and distributes wristbands to make sure they don't split shifts. Sometimes Dan Cathy, the president and chief operating officer, shows up in Chick-fil-A pajama pants.

"There's no better way to get to know your customers," said spokesman Mark Baldwin.

John Ruck, an 82-year-old retiree in St. Petersburg, Fla., has road-tripped to 48 Chick-fil-A openings __ not for the coupons but for the camaraderie. He went to his first in January 2006, while grieving his wife's recent death, and found them therapeutic.

He said he doesn't mind sleeping in parking lots because he brings a comfy chair. The only time he suffers is during the karaoke. "I've never been subjected to such torture for 52 meals," he said with a laugh.

Still, Ruck plans to keep coming "as long as the good Lord lets me," and compares the parking lot gatherings to a family reunion where he sees friends he's met at other openings. Last year, he drove more than 1,000 miles round trip to an opening in Louisiana, then turned around and did it again the following week.

Ruck is so enamored that he decided to make Chick-fil-A part of his wife's memory. A couple years ago, he had their wedding bands melted into one ring. When the jeweler asked him if he wanted an insignia, he had it stamped with the Chick-fil-A logo. Though his wife, Joanne, never slept in a Chick-fil-A parking lot, the chicken chain "was the only place she'd let the grandkids eat when she took them to the mall."

Skelton, who will stand beside the Chick-fil-A cow at his wedding, certainly understands the desire to marry his favorite restaurant fare with the love of his life. The managers at a Chick-fil-A in Concord, N.C., who will provide his bovine best man, are also enthusiastic, Skelton said. Conveniently, Chick-fil-A already has a cow tuxedo, which it designed last year for some marketing programs during the Oscars.

Skelton's fiancée, Heather Harmon, said she's on board too. "I'm more than OK with it, I'm super excited," said Harmon, a 26-year-old preschool teacher. "We'd been working really hard to put a lot of personal touches in this wedding. We didn't want it to be stuffy."