Bill Buchanan, a fit 24-year old from Massapequa, Long Island, disappears into the basement of Saloon, a sports bar on New York's Upper East Side. A few minutes later, he emerges wearing a gray wig, sunglasses, and an oversized button down shirt over a fat suit. The assembled crowd, packed tightly into the bar, spots him, cheers, and begins chanting "Zaun, Zaun, Zaun."

Buchanan has become something of an Internet celebrity thanks to his series of "Mike Zaun" videos, in which he impersonates WFAN radio host Mike Francesa in various historical settings, like the Civil War and World War II. (The name, Mike Zaun, is a play on the title of Francesa's show, Mike's On.) But Buchanan's character is particularly beloved by the mostly twenty-somethings at Saloon, who have gathered on the day before the Meadowlands Super Bowl for FrancesaCon, a day-long celebration of all things Francesa.

Buchanan makes his way to a table behind a barricade, where he's joined by Michael Benevento, the winner of a 2013 Chris "Mad Dog" Russo soundalike contest who became Internet-famous himself in 2007 for recreating verbatim a Russo rant about Pacman Jones. The real-life Francesa and Russo split up in 2008, with Francesa keeping the drive-time slot on WFAN and Russo moving to satellite radio, but their impersonators are teaming up on this day for a mock broadcast at FrancesaCon, and the hundreds in attendance are eating it up.

As their show is about to begin, the old Mike and the Mad Dog theme song -- They're talking sports, going at it as hard as they can -- plays over the loudspeaker, and the crowd, crammed shoulder-to-shoulder, sings along with every word. Benevento does Russo's customary intro from the WFAN era ("Aaaaaaaand, good afternoon, everybody!"), and the crowd erupts. A few minutes later, he gives out the old WFAN phone number to the "listeners," and the crowd cheers that, too.

But Buchanan is the focal point of the show, if only because the guy he's impersonating is the man of the hour. The crowd laughs at and cheers each Francesa-ism -- talk of a "trivier" game, put-downs about the Jets, drinking from a Diet Coke bottle with the label removed. And many of those in attendance have worn Francesa-related costumes: Lots of gray wigs, a few mitres (in honor of his nickname, the Sports Pope), and an assortment of homemade T-shirts (one has a photo of Al Albuquerque, the Major League pitcher whose name Francesa once accused a caller of making up as a prank). One guy wears a full-body Diet Coke costume, and commits to the character by drinking Jack and Diets all day.

The 60 year-old Francesa is not in attendance, which is no surprise considering the way he has often dismissed anything and everything written about him on the Internet. But his fans are out in full force on this day, and they're enjoying every minute.

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That FrancesaCon drew more than 500 people would only surprise those unfamiliar with his obsessive, sometimes bizarre (but always creative) online following. A parody Francesa Twitter account has more than 30,000 followers. The most popular of Buchanan's "Mike Zaun" videos, one in which his Francesa character travels back to 1776 to discuss the Revolutionary War, has more than a quarter-million views.

There's a Mike Francesa message board. And for years, a dedicated fan uploaded hundreds of choice Francesa clips to YouTube, then Tweeted out links, fueling online conversation and more than a few laughs at the host's expense.

Established media outlets eat this stuff up, too. When Francesa takes time out to show off his Super Bowl swag pack, or appears to fall asleep on the air, or rails against paternity leave for 20 minutes, it becomes a story beyond Francesa Twitter. But it's this online community -- "mongos," they call themselves, using a politically incorrect abbreviation of the word "mongoloid" -- that dissects every possible aspect of Francesa's show.

When Russo left WFAN in 2008, Mike and the Mad Dog was the top-rated show in its timeslot, and it was unclear whether Francesa would be paired with a new on-air partner or host the station's afternoon show by himself. ESPN's Bill Simmons -- who once penned an ode to the duo in which he called Mike and the Mad Dog "my favorite radio show ever" -- was approached by Francesa to host with him. There was even talk of holding public auditions at a New Jersey bar.

But Francesa remained No. 1 on his own, and eventually talk of a new co-host went away -- perhaps because WFAN executives knew that it would be impossible to re-create the chemistry Francesa and Russo had developed over 19 years together. Francesa's still atop the ratings today, but his solo show has a different tone than the one he hosted with Russo.

"They were a good mix," says Benevento, 37, the Mad Dog impersonator. "Russo was the wild, crazy one, and Francesa was like the straight man, which is the perfect comedy pairing. I think since Russo left, Francesa's become a little bit more full of himself. I think Russo grounded him a little bit."

Adds Benevento: "Russo had a sound-alike contest. Francesa would never do that."

The start of Francesa's solo show also roughly coincided with the rise of social media, and the television simulcast offered these fans the opportunity to watch the host as he worked, rather than just listen. Indeed, at FrancesaCon, I couldn't help but notice how often fans talked about watching his show, as opposed to listening. (Francesa's show was broadcast for years on the YES regional cable network; since earlier this year, it's aired nationally on the Fox Sports networks, though ratings have been tiny so far.) It's the paradox of Francesa: He's an old-school host working in an old-school medium, but his show is nevertheless a hit with plugged-in millenials.

Francesa's developed a reputation not just for strong takes on the topics of the day, but as an arrogant host who can be hard on his callers. (As one fan told me at FrancesaCon, "Mike Francesa is the most knowledgeable person I know, but his ego makes him just as famous.") In Tim Sullivan's history of WFAN, published last year, Francesa says that "I can be challenging to [callers], give them a hard time. My theory has always been that I treat the caller completely different than the audience." He went on to say that while he has "nothing but complete adoration" for his listeners, the ones who call in have decided they want to be a part of the show, and that makes them performers who need to bring their A-game. "With that comes responsibility," he explains, adding that "I may be short and contentious sometimes, but I'm being real."

It's a phenomenon that has the potential to be mutually beneficial. Last week, CBS Radio (which owns WFAN) pulled 88 videos from a YouTube account operated by a Twitter user who formerly went by the handle @WFANAudio. The videos were taken down because of copyright violations, and though hundreds of other clips still remain, the user said he won't be uploading any new ones. But the incident called attention to something that had previously gone mostly unsaid: That user -- and really, all the other Francesa fans on the Internet -- had only served to make the show more popular. @WFANAudio, as Deadspin put it, was Francesa's most effective marketer.

The man behind the @WFANAudio Twitter feed, who asked me not to use his real name, told me last week that WFAN would be better off embracing all the things people like about his show, and providing those clips themselves -- not just full interviews (which they post on their website), but the sillier moments his fans love to share. "If WFAN put these clips on demand on their site or via another platform, the amount of hits they'd get would be higher than what they think it would be," he said via email hours after the videos were pulled from YouTube. "Go ahead, sell ad space on the clips. People would still listen and you'd be able to monetize it."

See, in speaking with Francesaphiles, I've found the ones who goof on him the hardest are his most devoted fans. They like that he's a blowhard. They mock because they love.

Not that that's always been clear to Francesa. "I think that it takes him some getting used to that it's all out of love, because people do make fun of him, but it's kind of the way you make fun of a family member," says Michael Leboff, 23, one of the organizers of FrancesaCon. "You don't not make fun of a family member because they're a family member. You still love them, but you joke around with them."

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For a long time, Francesa wanted nothing to do with this internet community. Buchanan (a.k.a. Mike Zaun) explained it to me this way last fall: "The way he views the internet is -- he literally views the internet as one person, and that one person has made fun of him, and he does not like that one person."

But Francesa's attitudes seemed to soften a bit earlier this year, right before FrancesaCon. He'd previously dismissed callers who wanted to ask him about the event, but a few days prior, he mentioned it on the air, and even held up a T-shirt -- sold by the website Barstool Sports -- with his image on it, above the words "Numbah One." He didn't seem to grasp that the shirt was having some fun at his tendency to talk about his own success, but he held it up for the YES cameras nonetheless, explaining that his kids had seen it and wanted their own.

And though he didn't stop by FrancesaCon, he knew what was going on.

Mike Goldstein, 55, is better known to WFAN listeners as Mike from Montclair. He estimates that he's called into Francesa's show some 500 times over the past 20 years, and he's such a regular that he sometimes exchanges phone calls and texts with Francesa off the air.

Goldstein attended FrancesaCon, and he texted the host updates and photos as the day went on. He showed me his phone at one point, and one reply from Francesa, in particular.

"Amazing," it read.