What's scarier, the movie or who's watching it?

What's with young kids going to scary movies and playing scary video games? Lately I've had a few young classmates of my kids talk about their favorite R-rated movies like watching this stuff was the most normal thing in the world for a 12- or 13-year-old. When I say something unbearably fuddy-duddyish like, "Isn't that rated R? You shouldn't be watching that!" they seem genuinely bewildered. I can't quite decide if their parents don't know what they're watching or don't care, but man -- kids that young just do not need that stuff in their brains.

I was explaining this to a sixth-grader at my kids' school, a big fan of the movie "Training Day," who was appalled that I not only did not let my son play violent video games like "Grand Theft Auto," but that when a friend had brought it over, I made them stop playing and remove the offending game from the machine. "Wasn't your son embarrassed? Couldn't you have just waited until the kid went home?" No. And no. One viewing of that stuff is too much. And a boy like my son, who regularly sucks his fingers, jumps, and flaps, is probably beyond embarrassment. But it's true, too, that his friends know me, and know what Mama don't allow. Am I the last nay-saying mom around?