The bright future of 'It's Always Sunny in Philadelphia' -- The cast from the unlikely hit dish on their upcoming holiday DVD

You know the saying: Christmas just isn’t Christmas without a sweaty, buck-naked Danny DeVito.

At least, that’s how the It’s Always Sunny in Philadelphia gang is hoping consumers will feel this holiday season. On Nov. 17, 20th Century Fox Home Entertainment will release A Very Sunny Christmas, a holiday-centric DVD special that features a masturbating Claymation figure, a bloody confrontation with a mall Santa, and the ever-festive prostitution story line. So…merry Christmas to all! Well, almost all. ”Let’s put it this way,” DeVito says. ”No one at Jerry Falwell’s university…is watching our show.”

Perhaps not, but millions of others are. Now in its fifth season, FX’s comedy about five deranged losers — played by Rob McElhenney, Glenn Howerton, Charlie Day, Kaitlin Olson, and DeVito — who run a Philly pub has performed its own Christmas miracle: It has become TV’s biggest surprise hit. Not only is the series one of Hulu’s most-watched programs, but Sunny‘s ratings have increased 49 percent from last season in the coveted 18-49 demographic, with the show attracting almost 2 million viewers. And Sunny‘s fans are among the most rabid you’ll find. Legions of admirers have marched in Halloween parades dressed as the show’s unofficial mascot, Green Man. Hundreds have posted homages to ”Day Man” — a catchy tune written for a season 3 episode — on YouTube. And this summer, devotees packed theaters to attend the sold-out live tour of Sunny‘s season 4 musical finale, ”The Nightman Cometh.” ”It’s a whole new day for the show,” says FX president John Landgraf. ”It’s just one of those word-of-mouth cult phenomena. I have never heard of a show growing 50 percent in season 5.”

Not bad for a comedy created on a shoestring budget. Back in 2004, friends and out-of-work actors McElhenney, Howerton, and Day taped a pilot (written by McElhenney) for less than $200, using low-grade cameras and makeshift lighting. The pilot — originally titled It’s Always Sunny on TV and centered around actors in Los Angeles — attracted the attention of FX, who suggested the trio tweak their setting since new comedies like Entourage were already lampooning Hollywood.

Good thing Philadelphia native McElhenney had a backup plan. ”Philly’s sandwiched in between D.C. and New York, and I think that ultimately we’ve always had a little bit of an inferiority complex,” says the actor, who also decided to add Olson to the cast for a female perspective. ”I think that oftentimes we overcompensate in a lot of different ways, and I think that’s what the characters are doing too.”

In the first season, that overcompensating led to Charlie (Day) faking a terminal illness, Dennis (Howerton) attempting to seduce multiple women at an antiabortion rally, Dee (Olson) dating a high schooler, and Mac (McElhenney) becoming jealous after discovering a childhood gym teacher may have molested several peers instead of him. Such wildly un-PC story lines might just be one of the reasons Sunny debuted to mostly negative reviews and mediocre ratings (season 1 drew just over one million viewers).

Yet the show still picked up its fair share of supporters, like future cast member DeVito. The veteran actor (whose last regular TV-series credit was Taxi in the early ’80s) was already a fan when Sunny‘s creators lured him into starring as Dennis and Dee’s wacky, self-absorbed father figure, Frank. Gradually the viewers came around as well. ”Some people got it, and some people thought, ‘Well, this is kind of crass,”’ says Howerton, who shares writing credits with Day and McElhenney on the majority of episodes. ”[But] if you’re really paying attention, you realize it’s not just a crass show where people are trying to shock people by making dick jokes.”

Because while the Sunny gang writes plenty of gags about both the male and female anatomy — we’re talking about equal-opportunity offenders here — they also revolve their episodes around headline-making topics like the mortgage crisis, gun control, and North Korea. In fact, Day says they get most of their inspiration from listening to NPR. ”If anything ever turns the corner where it’s just kind of shocking for shock value’s sake, or dirty with no reference, it’s not funny to us,” Olson says. ”Poo-poo and wiener jokes aren’t that funny. But when you can find a way to make the wiener do something funny, now we’re talking.”

But even as its numbers and notoriety grow larger, Sunny still remains a small operation. Appropriate, considering the group is quite literally a family. Day is married to fellow cast member Mary Elizabeth Ellis (who plays ”the waitress,” the object of Charlie’s unhealthy obsession), while Olson and McElhenney wed in Malibu in September 2008. The crew will also be married to the series until at least 2012. Last summer, FX ordered enough episodes to guarantee Sunny fans a minimum of seven seasons. Add to that the fact that Comedy Central recently nabbed syndication rights — the first time a basic-cable network has picked up a comedy series from another basic-cable network — and Sunny’s forecast sure seems bright.

As for A Very Sunny Christmas? Since the sitcom has traditionally performed well on DVD (the Complete Fourth Season DVD has already become ”a top 10 performer among TV live-action comedies,” according to 20th Century Fox), droves of fans are likely to pop in the gang’s Christmas special this holiday — behold the sight of one big full moon. ”Sometimes I’ll go, ‘Oh, s—, man. I gotta get my ass out naked on the couch?”’ DeVito says. ”And then I go, ‘Well, where am I? I’m in this world with these guys and the bar. Yeah, that’s exactly what would happen.”’