HOUSE OF HORRORS : Entertainment: Balboa Cinema’s cast of characters make a show of imitating art and “devirginizing” first-timers at the weekly “Rocky Horror Picture Show.”

Forget about buying Milk Duds and buttered popcorn for this movie. You’re better off with an umbrella. Or if you want to get in on the action, bring some rice, slices of toast and a cigarette lighter.

Don’t worry that the movie won’t be shown in Dolby Stereo, either, because you won’t be hearing much of the dialogue. Instead, almost everyone in the theater will be too busy shouting responses to the film’s script.

This is “Rocky Horror Picture Show,” a weekend tradition at about 175 theaters across the country. Since 1978, the Balboa Cinema has been the Orange County home of the zany movie where fans arrive in costume and movie-goers bring scenes to life with props, such as rice thrown during a wedding scene.

“Rocky Horror” is more a performance than a movie, because during screenings, art imitates art. A “cast” of volunteers stands on the Balboa’s small stage and acts out the scenes shown on the screen behind them.

As an appetizer, “virgins,” those who have never seen the movie before, are sacrificed. They are brought on stage to be embarrassed for the audience’s amusement, before being allowed to return to their seats.

It’s all part of the madcap weirdness that brings 200 to 300 people to the Balboa, week after week, for midnight shows on Friday and Saturday.

“It was different from going to a movie and just sitting there. For once, you were part of the experience, you were responsible for creating the fun,” said Bill Ung, explaining why he kept coming back to see the movie after first attending almost two years ago.

The 22-year-old Huntington Beach engineer now plays a Transylvanian with Midnight Insanity, the cast that rehearses twice a week and acts out scenes on Saturday nights. There is also a separate Friday-night cast.

The film is about an accidental encounter between a clean-cut, sexually repressed couple, Brad and Janet, and a castle full of Transylvanian conventioneers from the planet Transsexual. When head transvestite Dr. Frank-N-Furter arrives on the scene, Brad and Janet fall under his spell.

The movie flopped when it was first released in 1975. But when marketed as a midnight movie, it quickly grew in popularity and now is shown across the country. To celebrate its 15th anniversary in October, 20th Century Fox held a party in Hollywood for fans and stars of the movie. Attendees of Balboa screenings also held their own local party with cake, prizes and a costume contest at the theater.

The degree of antics varies from theater to theater. And the Balboa, the only theater in Orange County showing the film, has a firm reputation.

“People who have been there tell me it’s a terrific show, and as good as any of them that are around,” said Tim Deegan, the film’s publicist and the man who originated the idea of showing “Rocky Horror” as a midnight movie. “There’s a lot of young, fresh talent at the Balboa, which is very exciting.”

But the glory doesn’t all go to the cast. This is an audience-participation movie, something that developed spontaneously in theaters shortly after “Rocky Horror” began showing at midnight, Deegan said.

There’s a running commentary from the audience that begins almost as soon as the first screen character speaks. When Frank-N-Furter pauses when saying, “anticipation,” the audience calls out for him to finish: “Say it!”

When Brad walks past his car’s flat tire, just before he moves his foot, the audience reminds him to “Kick it!”

Balboa Cinema manager Mike Peterson says the yelling is a chance for people to express themselves without fear of ridicule. A funny line can make the audience burst into laughter. “And if it doesn’t work, no one knows where you are,” Peterson said.

For filmgoer Mike Herron, a 17-year-old high school student from Santa Fe Springs, “Rocky Horror” is a cathartic experience. “It’s the only place where you can yell in a movie. It releases all your stress,” he said.

It’s not only vocal. The audience also aids in making screen events real. When rice is thrown at the film’s wedding, rice is also being tossed across the theater. When it rains in the movie, it pours inside the cinema as audience members squeeze the triggers on their squirt bottles. Likewise, when Frank-N-Furter offers a toast at dinner, bread goes airborne.

And when the Transylvanians all do the Time Warp dance, the audience dances along.

The uninitiated might find all the craziness a little intimidating. In line on a recent Saturday night, four “Rocky” virgins looked as if they were having second thoughts. While others around them were decked out in costumes or dark clothing, they stood out like beacons in denim jeans and white T-shirts. Lest there be any doubt they were first-timers, a self-appointed roving band of regulars inked their foreheads and cheeks with Vs.

“I’m freaked out. It’s weird. All these people are dressed up weird,” said Christine Wright, 18, of Covina, looking at the others in line.

But her friend, Carmen Falcon, 19, of Victorville, reflected: “I think we feel weirder than they do!”

Soon the more timid will be able to see “Rocky Horror” in the privacy of their own living rooms. A legitimate video copy of “Rocky Horror” (many devotees have bootleg copies) will finally be released on Nov. 8. To many fans, it’s close to sacrilege because the movie has always been inseparable from the experience of seeing it in a theater.

“Just watching the movie is nothing like the experience,” cinema manager Peterson said. “It’s the difference to listening to a play on tape and seeing a play.”

Sensitive to this concern, the video has a short prologue filmed at different theaters across the country to educate video viewers of the “Rocky Horror” experience. And the Balboa gets a nod when, by chance, its marquee is featured both in the prologue and in a music video of the Time Warp dance at the end of the tape.

No doubt when those watching the tape are ready to try the Time Warp, they’ll find regulars at the theater waiting to “devirginize” them and welcome them to the world of “Rocky.”

“I think the Balboa is going to go for a long time,” publicist Deegan said. “They have terrific leaders and tremendous enthusiasm.”