When “This is Spinal Tap” premiered twenty-five years ago, the now classic mock-documentary…or “mockumentary,” if you will…about lightly-brained, heavily sedated British metal stars on the skids received good reviews but unexciting box office. Considering that most people who saw it – and understood that it wasn’t a real documentary — thought it was one of the funniest movies they’d ever seen, it wasn’t too big a surprise that it soon became a very significant cult hit via home video. What was a bit harder to predict was that a film featuring three only moderately well known comedian/satirists and directed by then first-timer Rob Reiner would become one of the most influential comedies of its era. It certainly wasn’t clear that lines such as “this goes to eleven” or “it’s such a fine line between stupid and clever” would enter the general musical and cultural lexicon, and that, decades on, “mock docs” would remain among the most popular of low-budget movie subgenres — and not only for comedy.

Still the biggest surprise of all was that, as musicians, improv geniuses Christopher Guest, Michael McKean, and Harry Shearer, turned out to be better at music as a sideline than most of those who do it fulltime. Not only could the trio play rockers like “Big Bottom” and “Sex Farm” live with brio and dexterity, “unplugged” versions of such vintage Tap classics as “Listen to the Flower People” and “Give Me Some Money” were among the highlights of their early live shows. Of course, the shows were funny, but the big surprise was how well played the music actually was, wowing both metalheads and metal-haters (that would be me) alike.

It didn’t end there. With Christopher Guest emerging as the most reliable comedy-mockumentary director of his time with such irony fests as “Waiting for Guffman” and “Best in Show,” Guest, McKean, and Shearer became the Limelighters/Kingston Trio-like Folksmen. The group figured prominently in Guest’s affectionate 2003 poke at the folk music scene, “A Mighty Wind,” leading to the inevitable gigs where the geeky but oddly talented folk music threesome would open for the bombastic boy-men of Spinal Tap.

Six years later, however, Guest, McKean and Shearer would, in preparation for an upcoming Spinal Tap reunion, take the ultimate step of acoustically performing a collection of Tap and Folksmen classics as well as new material not as any of their off-kilter comedy personas, but as themselves for this spring’s 30-city “Unwigged and Unplugged” tour, which is now officially underway.

As the three performers proved at a promotional press conference held at West Hollywood’s House of Blues last month, however, just because they’ll be working out-of-character doesn’t mean they’re not characters. Talking as their real-life selves, the quips and gags rained onto the assembled journos, steadily drawing laughs from some of L.A.’s jaded showbiz observers.

Asked by the event’s emcee, MTV’s Kurt Loder, about the reasons for performing such classics as “Hell Hole” and “Blood on the Coals” sans costuming, McKean, who played the tall and ridiculously blonde lead-singer David St. Hubbins, took the lead. “We’re doing the trio tour because it’s so easy,” McKean said. “We just have these wooden instruments, and we don’t have to wear things on our head…unless we’re playing a temple or something.”

“I think it occurred to us [when] we did a show in New York about three years ago,” added a slightly more somber Christopher Guest, a.k.a. resolutely ignorant lead guitarist Nigel Tufnel. “….It not only included Spinal Tap music but also included ‘Waiting for Guffman’ music and ‘A Mighty Wind’ music. It was fun to play acoustically. The songs sounded a little different, but it was simpler. It was fun.”

Opening the floor to questions from the assembled press, your intrepid reporter was determined to get at least one question in: Had any of the guys written a completely non-ironic, non-humorous song? (If I’d been less distracted, I would have noted that Christopher Guest has been collaborating on jokeless instrumental music as one-third of the Beyman Brothers, but they politely answered my question anyway.)

“Michael has written a number of completely non-ironic songs. I am incapable of that,” said Harry Shearer, best known to some as laconic bassist Derek Smalls.

“I’m with you,” chimed in Guest. (Allowing, I suppose, that instrumentals aren’t really “songs.”)

But then McKean disagreed. “You wrote a couple of tunes that were kind of straight ahead,” he said to Shearer, naming a title Shearer had apparently forgotten. After a moment of light quibbling between them on that point, I asked if any of McKean’s “non-ironic” songs were publicly available, in any case. The answer was a quick “no.”

“They’re way too straight ahead to go on the market,” said McKean, though Shearer described McKean’s non-funny songs as “beautiful.”

That lead into discussions of the release date of the upcoming Spinal Tap material (perhaps this May) – the 10:30 a.m. start time of the press event, and whether any of us in the audience were already drunk. (For the record, I don’t think the HOB bar was yet open, though I can’t speak to the presence of flasks or airplane bottles.)

Then, someone had the temerity to mention a younger competitor to the Spinal Tap/Folksmen musical parody crown, Flight of the Conchords.

“You mean the guys who beat me for the Grammy nomination? I’m such a fan,” said Shearer, referring to his own politically themed “Songs of the Bushmen,” drawn from his long running radio showcase, “Le Show.”

“Why don’t you just bring up the Holocaust, man?” said a mock-angry Michael McKean, who added that he had seen them live a few years ago prior and thought they were “very, very funny, but…it’s like parallel universes.”

After that, somehow the subject became the question of who currently owns the rights to “Spinal Tap,” which first originally belonged to the long-defunct Embassy Pictures and later passed through a number of conglomerates. “We were once owned by the company that owns L’Oreal Cosmetics,” said Shearer.

McKean then interrupted with “You know Legos, you know those toys?” But then he corrected himself. “We actually were owned, as Harry was going to say, by a company called Parafrance which, while we were negotiating with them, several of the chairman of the board…were revealed to be Nazi collaborators.”

Abandoning the past, host Loder brought up the future. “Is there anything planned beyond this tour, or is this it?”

“Well, I think the world goes on, is that what you mean?” responded Guest.

“We’ll be bombing Iran,” added the politically minded Shearer as Loder tried to refine his question.

That somehow led into a question about cover versions. “We’ve only done a few covers,” said McKean. “Before we did [the Rolling Stones’] ‘Start Me Up’ as the Folksmen, we used to do “Flashdance — What a Feeling” as the Folksmen, and it was really fun to do….The fine line between nausea and nostalgia was nowhere more evident.”

Asked about possible guest-players on the upcoming Spinal Tap recordings, the answer was that a number of guitarists might be appearing on a new studio recording of the twenty-minute long metal magnum opus, “Short and Sweet.”

A lull followed, so I took the opportunity to ask another silly question. “Do you find that ‘unwigged’ you play differently?” I said, unconsciously making a gesture with my right hand that mimicked the removal of a wig. My motion provoked some teasing from Harry Shearer to the effect that I had mimed the removal of a wig, but had failed to imply guitar playing via hand gestures. (In my defense, my other hand had my tape recorder in it.) He did eventually answer the question, rather thoughtfully.

“We’re approaching these songs almost as if we’re covering them, because we can’t do the same versions, and we’re not playing these characters. We’re making, now, some of the choices as ourselves, as opposed to when we’re in those characters, when we’re making choices we think they would make….”

“So, we now make choices we would make,” chimed in McKean.

“Yeah, we have ask ourselves ‘what would we do?’” Shearer concluded.

From there, the discussion turned to other mid-eighties metal bands such as Iron Maiden and Def Leppard, and wound up with Kurt Loder praising the Tapsters for not hitting the nostalgia circuit with other once popular hard rockers turned musical bottom feeders. Were the boys ever tempted to so cash in?

“The only temptation is get to hang with Yngwie J. Malmsteen again,” confessed McKean. “Because now with the ‘J’ in his name we won’t confuse him with any other Yngwie Malmsteens.”

That led to some philosophizing about the meaning of “This is Spinal Tap,” a quarter century later.

McKean: “It’s a cautionary tale that we don’t intend anyone to pay heed to. It’s so much fun. If you’re a young guy and you want to be in a rock and roll band, see this movie but do it anyway.”

“I would say that also about ‘Big Momma’s House,’” Guest added.

And that was a deep thought that Shearer built on. “Over the years, I’ve run into a lot of kids who’ve said [that] ‘our band learned what not to do by watching your movie.’ So, it is an educational film,” added Shearer. He also added with some audible pride that he’s heard from country, jazz, and even classical musicians who felt the film had something true to say about the musician’s life.

And that led to a question about what’s really important: will Spinal Tap songs ever end up on “Guitar Hero.” The answer is they already have and more may be in the offing, which led Christopher Guest to add that mastering a Spinal Tap song on the popular game is “way harder than actually playing it.”

Which led to the inevitable discussion of the so-called rock and roll lifestyle. Guest took that one. “When we were going out as Spinal Tap, and the first tour was in ’84 and we did several others, we just played these shows. Now as these guys [Guest points out how relatively normal and mature the three of them appear] we’re going to destroy hotel rooms.”

“Actually,” said Shearer, “at our age, we’re going to hire people to destroy them.”