The cult film known as The Rocky Horror Picture Show celebrated its 40th anniversary last month. Having racked up more than $100 million in lifetime earnings, the movie still plays weekly in 75 theaters around the U.S., according to The New York Times

Why has Rocky Horror endured for four decades? With Halloween approaching, it's only proper to examine how this "horror" movie was well ahead of its time as a customer experience.

A Place to Scream.

If you've never seen it, here's how Rocky Horror typically plays out in theaters: At most midnight showings, superfans show up dressed as characters from the film (see photo above) or just plain dressed up, Halloween-style. If you haven't come with a costume, don't worry--the superfans will equip you with a spiked bra or a gaudy necklace. 

During the film, fans both improvise and add premeditated punch lines to the dialogue, shouting their lines so the whole theater can hear--and usually, laugh. For example, before a character says, "You see," fans--who know when the line is coming--will shout the letter "F." The audience effectively hears the letters F, U, C in rapid succession. Can you guess which letter the superfans shout next?

In other words, unlike most movie experiences that involve passive watching, Rocky Horror is interactive entertainment--and that's key to its appeal. 

University of Pittsburgh sociologist Margee Kerr, who specializes in the study of fear, says this interactive experience is something people crave.

"This is a generation raised without a lot of active engagement," Kerr says. "Less time just going out and playing. Everything is so virtual. A lot of people missed out on the active part of things and want to get their hands messy."

A Place to Participate. 

From a branding perspective, Rocky Horror is the rare film that has moved away from the traditional art of storytelling (a term that's all the rage in branding) and into the realm of storymaking.

Storytelling is when a brand simply monologues its tale, writes David Berkowitz, CMO with Manhattan branding consultancy MRY, in an Ad Age column called "The Beginning of the End of Storytelling." Storymaking, on the other hand, means gathering tales about how your brand has become a part of your audience's true-life experiences. It's a collaborative process between a brand and its customers.

The example Berkowitz uses comes from his wife, Cara. When he asked Cara about her love of the Coca-Cola brand, she explained how she and her friends in sleepaway camp would break off tabs from Coke cans to reveal which boys they liked. In other words, her story was not about the brand per se. It was about how the brand had been a meaningful part of her youth.

Rocky Horror superfans have made moviegoing a participatory, storymaking experience--as opposed to the passive storytelling experience traditionally found at the movies. No one who has lost his or her Rocky Horror virginity forgets what that night was like. Usually, your friends help you remember, reminding you about the time you wore a bra on your head.

What's more, because of all of the live-action spontaneity, every viewer's experience of Rocky Horror is distinct; no two nights are the same. "People still come up with audience participation lines week by week," Larry Viezel, a superfan who helped produce a documentary called Rocky Horror Saved My Life, told The New York Times. "There are lines that are going to be about Donald Trump, and the other day there was a line about Cecil the Lion. Whatever is in the news can become an audience participation line."

A Home for Misfits Everywhere.

Actress Susan Sarandon, who starred in Rocky Horror, compared the experience of seeing the movie in a theater to a Mass. She told The New York Times that the film has "given a home to so many people, especially those who need to be accepted for who they are."

After all, this was a 1975 film in which a character called Dr. Frank-N-Furter (played by Tim Curry)--who dubs himself a "sweet transvestite"--has a key role. That still doesn't happen so often in the movies--or on television or in books or on magazine covers. 

It's easy to see the link between Curry's character and the superfans' vibe of campy tolerance for all moviegoers--regardless of what they look like or whether they are virgins to the Rocky Horror experience. It's an ethos of inclusiveness almost any company hoping to make memories can learn from.