Forget about 11: Nigel Tufnel can now say, "This one goes to 25."

That's because Monday marked the 25th anniversary of the release of Rob Reiner's classic comedy "This is Spinal Tap," a mock "rockumentary" that follows a waning British heavy metal band on what appears to be the final tour of their career.

The core trio of the group consisted of lead guitarist/singer Tufnel (Christopher Guest), rhythm guitarist/singer David St. Hubbins (Michael McKean) and bassist Derek Smalls (Harry Shearer). Reiner played "rockumentarian" Marty Di Bergi who follows the band around as its tour hopelessly falls apart.

Co-written by Reiner, Guest, McKean and Shearer, "This is Spinal Tap" developed a major cult following after its release, which eventually grew into a parallel universe of sorts. Fans of the movie could become fans of the group in real life as Spinal Tap began playing real-life concert gigs. In fact, Guest said in a 2000 @ The Movies interview, as the years have rolled on, the shows have even attracted a second-generation of Tap admirers.

"When we go out and perform as a band, it feels like it did when we were playing on the road in 1984," Guest said. "It has the same feeling, except for the fact that people watching it are the kids of the original people that watched the film. It's odd."

But concerts weren't the only form of entertainment Tap brought to the masses. In 1992, they released the album "Break Like the Wind" and appeared together for a television special "The Return of Spinal Tap." Plus, they did voice gigs as the group for an episode of "The Simpsons" and the movie "Small Soldiers."

And for the DVD debut of "This is Spinal Tap" in 2000, Guest, McKean and Shearer did the audio commentary in character which resulted in an effort almost funnier than the film itself. The rockers were even immortalized in plastic the same year, as California company Sideshow Collectibles released 12-inch Spinal Tap figures -- the accessories of which included miniature Tap albums and an amplifier knob that went to 11, of course.

Taking the movie-real life parallel universe one step further, Guest, McKean and Shearer have also performed in public as The Folksmen -- the trio of reunited folk musicians featured in the hit 2005 documentary-style comedy "A Mighty Wind." But in an @ The Movies interview for the film, McKean said that the opening gigs the group did for Spinal Tap didn't connect with audiences right away because The Folksmen's film debut was still quite a few years away.

"We fantasized that The Folksmen were the most poorly booked opening act for Spinal Tap you could ever imagine, so we used them in a TV special we did in '92," McKean said. "But while you got to see them rehearsing, they get bumped from the concert. So in 2001, we said, 'Let's really do this.' We did about 10 gigs all together and we opened for ourselves for about five of them."

But there was one big problem: McKean, Guest and Shearer forgot to let Spinal Tap concertgoers in on their opening act at the Beacon Theater in New York in July that year -- a mistake that almost got the old folkies booed offstage.

"When we played Carnegie Hall that June, we had a picture on the Spinal Tap poster that featured the special guests, The Folksmen. People who looked at the poster for more than 10 seconds got the joke," McKean recalled. "But we forgot to do that when we came back to play the Beacon. We looked at the audience and said, 'Oh my God, we're in trouble.' But it's exactly what those guys would be going through if they were actually opening for Spinal Tap. It was a nice little psychodrama."

Spinal Tap got back together in 2007 when Reiner (as Di Bergi), well, tapped, his old friends to play the London gig in the worldwide series of Live Earth concerts. The show, among other tunes, featured such Tap classics as "Stonehenge," complete with the "Little Druids" who almost trotted upon the miniature replica of Stonehenge in the 1984 film.

Tap just announced that they will be back as a band -- of sorts. In April, Guest, McKean and Shearer said they will begin touring the U.S. and Canada as themselves -- "Unwigged & Unplugged."

While Reiner, Guest, McKean and Shearer have been the talent most associated with "This is Spinal Tap" over the years, the movie is remarkable in that it showcased many established actors -- as well as others early in their careers. The crop of cameos and small roles in the film includes the likes of Billy Crystal, Dana Carvey and Paul Shaffer. Fran Drescher had a role in the film, too, years before she hit sitcom gold with "The Nanny."

"At the time I knew there were fantastically talented, interesting people on the rise, and I definitely wanted to be a part of it," she recalled in a 1999 interview. "Since there was no budget for the movie, we had to supply our own wardrobe, and there were no dressing rooms. We were really roughing it. But because it was such a creative endeavor, I just wanted to roll up my sleeves and get into it. I'm very grateful that I did, because it turned out to be this unbelievable cult classic. I'm very proud that I was a part of it."

So what are the stars of "This is Spinal Tap" up to today? Click into our slideshow to find out.