Pretty old story. I saw it on a special a while back. It's still pretty fucked up.
From what I remember, I think they lured her into the woods when they were all playing and demanded that she showed them her parts. What upset me the most was that the father of one of the boys was shown saying that she "wanted" to participate in it. Parents like that have no business raising children, in my opinion. What happened to teaching your kids wrong from right, morals, consequences, and just plain not exposing them to an adult environment that they have no business being in in the first place??
I feel safe in assuming that the parents of at least one of these little shits were probably porno-watching lowlives who didn't care much when it came to keeping up with their children and being a role model for them. When I say "porno-watching lowlives," I mean that, more than likely, the kids probably had access to the material or it was being watched around them. Kids by nature are curious. If you show them things like that (which you shouldn't in the first place), the kids are going to pick up on the behavior and wonder about it. Then when you don't explain to them, they more than likely are going to go to their friends with it and come up with dumb ideas. Such as this.
Be smart, bitches! Teach your kids about sex, especially if you're dumb enough to leave material around.
/rant