Twenty-eight years after its mostly unnoticed release, “The Rocky Horror Picture Show” has evolved into the most celebrated cult classic of all-time. Though the film is not about Halloween, it has become permanently attached to this holiday much in the way that “It’s a Wonderful Life” is now synonymous with Christmas. Somehow, just as the god-fearing Jimmy Stewart seems to represent the Christmas spirit, the cross-dressing Tim Curry simply captures the essence of All Hallows Eve. Attending a screening of “The Rocky Horror Picture Show” is unlike any other movie theater experience. Legions of devoted fans not only know the film by heart, they live it. Never is this more evident than on Halloween, when theaters across the country welcome the Rocky Horror faithful, young and old, for a night of uniquely interactive cinema. “It’s a pretty insane time,” said Joel Wukotich, assistant manager at the Cla-zel Theatre downtown. “We’ve been showing ‘Rocky Horror’ on Halloween for about seven years now, and its always something to see.” The Cla-zel will be hosting “The Rocky Horror Picture Show” again this Halloween, playing both tonight and Saturday night at 11 p.m. For veterans of the show, it marks an annual opportunity to dress as their favorite characters, shout at the screen and do “The Time Warp” again. For the uninitiated members of the audience, however, some of the “Rocky Horror” traditions may come as a bit of a shock. “The performers do a pre-show before the film begins,” Wukotich said, referring to the group of locals who take the stage in full costume, acting out scenes and leading the night’s festivities. “They bring people up on stage who have never seen the show before. They call them ‘virgins,’ and they basically humiliate them for a good five minutes.” Once all the newcomers have been properly introduced to the rules of Rocky Horror, the film itself can begin. Generally speaking, the film is about a young couple played by Barry Bostwick and a young Susan Sarandon. On their way to tell a friend about their recent engagement, they get a flat tire and end up spending the night at an extremely bizarre castle inhabited by a crew of equally bizarre characters. First and foremost is Tim Curry in the role of Dr. Frank-N-Furter, the “transsexual transvestite from Transylvania,” who seeks to create the perfect man. Following Dr. Frank around the castle are his neurotic butler Riff Raff (Richard O’Brien), fiery maid Magenta (Patricia Quinn) and motorcycle rebel Eddie (Meat Loaf), among others.

The plot may be mildly amusing, but it’s the colorful characters and outrageous musical numbers that have made “Rocky Horror” the longest running film in movie history.

Ironically, such longevity would have seemed ridiculous when the film bombed at the box office in 1975, but the unusual musical found a new audience and a second life at New York’s Waverly Theater the following year.

Running for many months as the midnight movie, “Rocky Horror” became an underground phenomenon of sorts, drawing strong audiences night after night. Eventually, with many of the same people in attendance at each showing, a miniature subculture of “Rocky Horror” devotees began to form, adding their own input and style to the images on the screen.

Within a few years, many movie houses across the country had recognized “Rocky Horror’s” surprising appeal and the audience participation traditions from the Waverly followed the movie to other cities. Soon enough, “Rocky Horror” fans from coast to coast were well versed in the interactive aspects of the show, from shouting one-liners at Susan