from www.washingtonpost.com – Quick poll. Watching porn while on public transportation is:

A. Acceptable.

B. Not acceptable.

On a recent cross-country trip from Los Angeles, Jana Matthews thought she’d lucked out when her friendly seatmate cued up a cartoon on his laptop. Her four children were enthralled; she hoped listening in might keep them occupied. Then the cartoon characters started doing things that cartoon characters should not be doing. Naked things. Naked, noisy things, unfettered by the restraints of human anatomy because the participants were, after all, hand-drawn.

After unsuccessfully trying to divert her kids’ attention, Matthews asked the guy whether he would mind watching something else. After a little grumbling, he put on some headphones and turned the screen away. But he was still watching. She knew he was still watching.

Porn vibes. In public. Flooding the recycled air of the plane.

The thing that skeeved out Matthews, an English professor, is that she’d had such a pleasant conversation with Porn Man before the plane took off. They’d talked about his Ivy League classes, about the math conference he’d just attended. “I had a significant amount of information about him,” Matthews says. They’d developed a little travel-size friendship. Then came the porn. And she was trapped.

It’s practically a human rite of passage to have a roommate — a slobby college one — who loves Jenna Jameson. This, we know how to deal with. (“Dude, turn it off. My lab group’s coming over.”)

But the increasing popularity of laptops and handheld devices, and the prevalence of wireless Internet access, means there’s a greater chance of becoming a bystander to a complete stranger’s viewing proclivities. Like being exposed to the cigarette smoke of a nicotine addict on the street, people are inhaling secondhand smut.

“To each his own is my policy,” says Debbie Shatz, a consultant who lives in Northern Virginia. That’s why, with rare exception, she’s remained unfazed every time she’s encountered porn on planes, choosing to quietly avert her eyes and ignore it, unless ignoring it becomes impossible.

Naturally, flight attendants, the front line of defense for any in-flight high jinks, have experience with this issue.

“We don’t walk through the cabin and give passengers a thumbs up and thumbs down” on what they’re watching, says Steve Schembs, a Washington-based flight attendant and local union officer. But when he notices that something is disturbing other passengers, he intervenes. “I’ve had 100 percent compliance,” Schembs says. “I have never had anyone say, ‘I refuse to stop. I must watch this dirty movie.’ ”

“You want to create the least amount of conflict possible at 30,000 feet,” says Renee Foss, the communications chairman for the Association of Flight Attendants, and a 24-year veteran of the skies. “Maybe a free snack box would give the passenger something better to do.”

Both flight attendants say instances of public porn are rare.

Last fall, some airlines announced they would work on filtering in-flight Internet access to prevent the surfing of inappropriate content (dirty DVDs brought on by passengers, however, would be nearly impossible to filter). But this secondhand smut can also happen on the ground. On buses. In gyms. In movie theaters.

“At a Wizards game!” says Dan Merrill, who works in accounting in Washington. “We were at a Wizards game and this guy was watching porn on his iPhone!” Odd on many levels, but there the guy was, kicking back, watching the sport, watching the other sport, just as he would at home.

Perhaps this is the real problem: the increasingly blurred boundary between public and private. If we are so accustomed to burying our noses in tiny screens, carrying our entertainment in and out of the house, perhaps people are simply getting confused as to where they are.

Could simple public service announcements clear this up?

ATTENTION: As similar as this basketball arena may appear to your apartment, they are not, in fact, the same place. For further evidence, please ask yourself the following question: Does my apartment typically contain 20,000 complete strangers? If the answer is “No,” then you are in a public arena. You should not be watching porn.

Those afflicted with secondhand porn say it’s not that they oppose adult entertainment. The trouble was knowing that they couldn’t escape it, not until the plane landed or the Metro doors opened.

That, and the general haze of gross that seemed to descend on the public space, the filmy yuckiness that made them wish the sprinkler system would spontaneously activate.

That, and the feeling that came with knowing exactly what was on their neighbor’s mind.

“It was like when a friend tells you too many details about their personal life,” says Jess Mortimer, who spent an eternity stuck in a Beltway traffic jam behind some guy watching really acrobatic stuff on his SUV’s television. (This type of secondhand viewing is prevalent enough to have earned its own terminology: Drive-By Porn. Several states have passed or proposed legislation dedicated to preventing it.)

“At some point . . . we’ve completely lost the ability to tell when it’s socially appropriate and when it’s not,” says Matthews, the mother of four. At her last job, teaching at a university in Pennsylvania, “I don’t think there was ever a time when I would do research at the library and someone wasn’t using a public terminal to watch porn. I’m trying to do research and you’re sitting there watching your . . . porn.”

Especially when the library was full, she was never quite sure how to deal with the situation. What’s the etiquette here? Shoot the offender dirty looks? Drag in a defenseless librarian? Innocently ask the guy how much longer his studies would take?

Or just make the best of a gross situation?

Sandi Benedetti, a bartender in Northeast Washington, was catching some extra sleep on a long morning Metro ride when a guy in a business suit took the seat next to her — the only one available on the rush-hour train.

“He sits down, reaches into this leather bag, gets his laptop, and suddenly I’m hearing Ah Ah Ah Ah AhAhAhAh!” She tried to ignore it, but the volume was loud enough for other passengers to hear it, too. “The guy in front of us turns back and glares at me! Like he thinks I’m with this guy! And then the woman across the aisle, too.”

She thought about saying something, or circling her finger at her temple in the universal crazy gesture — anything to demonstrate that she had no part in this guy’s morning wakeup call. But Benedetti is an adventurous gal, and as the train chugged on she began to ask herself when a bizarre event like this might happen again. “I was already being blamed for the porn anyway, so I figured I’d just play along.”

She leaned into her seatmate and started watching.

“Dude smiles at me,” she says, “and then we both just watch together. Stop before mine, he packs up the computer and gets off. We never said a word.”

Just two consenting adults, on their way to work.