CELL PHONES RINGING. Running commentary or full-on social discourse totally irrelevant to what’s on the screen. Exit doors opening and staying open way before the credits. And this is just during the 9:15 p.m. showing.

Truly, though, one of the signs of the Apocalypse must be when a mother brings her baby into a 10 p.m. Saturday showing of “The Exorcist.”

Movie patrons have long known that cramming together so many bodies in rows can give rise to an occasional discourtesy. But I’m talking unrelenting, nerve-plucking, downright rudeness.

Monica Allen, house manager at the Brenden Concord, has noticed that theatergoers are much ruder than they used to be. She has had theater-hopping parents who drag along their children, then start cursing in front of them when they get caught. The latest Allen has witnessed is people coming to fisticuffs over saving seats.

Some rabble-rousers do apologize for their disruptions. Others shut up only when the in-house security comes, and a defiant few have had to be dragged out by the police.

Practically every theater runs courtesy requests before the previews, but not all are as vigilant as the Brenden. The baby brought into the Oakland multiplex screening of “The Exorcist” inevitably began screaming, mom didn’t move, and no one booted them out. At a Berkeley screening of “The Cell,” a group guffawed and laughed not during the macabre scenes which would have made them sick and wrong but randomly, which just made them stupid and annoying. My friend handed the manager a business card and demanded a call explaining why this was allowed to happen. My government lawyer friend did receive an obsequious voice mail the next day, with the manager conceding that there had been complaints, but shucks, the theater just didn’t have enough people to monitor the crowd, although it wishes it could.

So much for our ushers of discipline.

Maybe the troublemakers believe higher ticket prices include the cost of mouthing off. Perhaps shrinking theater screens confuse them into thinking they’re in their living room. It could be they’re actually revolutionaries fomenting an intellectual crusade against Hollywood.

Or maybe these people are brainless folks who should be slathered with fake butter and tied down to those revolving hot-dog grills.

This brings me to my suggestion that wouldn’t require any changes in show times or screenings. Multiplexes would simply reserve one theater for rude people.

Of course, in an ideal world as in an ideally vengeful world impolite theatergoers would have their own special multiplex, a kind of moviehouse version of Dante’s circles of hell. So if there are any multiplex architects out there, consider these blueprints:

* Cell phone users strap themselves into executioner chairs a discount death row deal from the rapidly emptying Texas prisons and plug in their phones. Every time it rings, they get an energizing jolt of electricity.

* Laser light flashers sit under strobing lights with their eyelids taped back. The wavelength is increased to trigger Pikachu-like epileptic seizures.

* Women with lighthouse beacon fixtures on their heads climb up a steep, grueling hill to the balcony. As they ascend, monkeys will toss Hot Tamales into their hats. Then, once they get to the balcony, the hat falls down. They have to go back down to retrieve it, then make the climb again. And again.

* Instead of cupholders, talkers each have a bucket piped from the concession stand. It begins to fill with popcorn with salt granules the size and consistency of gravel. The talkers have to eat the popcorn, otherwise it’ll spill over and eventually bury them alive. That’s when the butter lava starts streaming down the walls.

* Parents drop their squalling babies at a day-care center with seemingly saintly baby-sitters. While the parents are enjoying the movie, the babies will be programmed into a courtesy cult a la “The Manchurian Candidate.” After reaching a certain age, the children will suddenly nag their parents every waking moment over every shred of incivility. The offspring themselves will be extraordinarily mannered, gracious, and will wash their hands after using the restroom.

Times events editor Vera H-C Chan tries to take the aisle seat so she doesn’t interrupt patrons when she has to excuse herself. She’s nice that way.