In my recent travels I was watching a movie that was Rated-R while I was on the train.
I was careful about it, taking a corner seat, with no one able to watch over my shoulder (high seats) and the screen turned away from the person next to me.
But while I was sitting there watching it, I thought to myself: “Should I really care who sees it? I am watching it. If they don’t want to see it, then don’t look at my stuff.”
And quite frankly, I was correct. (Of course I was, do you think I’d argue with myself? <On the other hand, I am currently conversing with myself [so off-topic by now…]>)
While reading this months Wired magazine (July 2014) I came across a great article on the topic written by Brendan I. Koerner, and for your enjoyment, I’m gonna put it here for you to read:
That was a full disclaimer…but in case it wasn’t clear enough…I DID NOT WRITE THE FOLLOWING PIECE, but I am fully endorsing the Wired magazine piece, and you SHOULD go out and get a subsciption to the magazine. HERE (you even get a free hat)
Thanks to tablets and new FAA rules you can now watch The Walking Dead from gate to gate. But should you? The person in the adjacent seat might be the sort who takes offense at anything racier than Dancing With the Stars, a show notably lacking in rotting flesh and beheadings.
The answer: It’s fine. Coach class isn’t a Puritan church service, and you shouldn’t feel ashamed about watching video with a little bump-and-grind. Your real concern is noise. “The biggest complaint we get about electronic devices, by far, is that they’re too loud,” says Shawn Kathleen, a veteran flight attendant who runs a blog called Rants of a Sassy Stew. We’re pretty good at keeping our eyes to ourselves while flying, but not so much our ears. So while an occasional flash of buttocks is fine, make sure that nothing audible (movie, music, or personal chortle) disturbs your neighbors.
The “images good, noise bad” maxim will also serve you well once cell phone service is allowed at altitude. Texting will be fine, but talking will be an offense punishable by feeding your bowels to the undead. —BRENDAN I. KOERNER
Aviously 
And when your kids see porn at 5 years old bc some guy was watching it in public, in the park or on the train, you’ll have no right to complian.
First off, pornography is not R-Rated.
Second, I’ve observed people reading that sort of material on a Kindle on the Subway (and I’m not referring to 50 Shades).
Third, that’s a whole nother issue, that is actually covered under the first amendment.
http://newyork.cbslocal.com/2011/04/25/watching-porn-at-nyc-libraries-is-ok-officials-say/
Lastly, why do you need to take it to extremes?
Fine, so you would be ok with your kid seeing American Pie over the shoulder of someone on the train?
Again, there is a difference between R-Rated and Uncensored. But if it’s R-Rated then my kid needs to just sit down and stop bothering the guy.