Sometimes teenagers go through a phase where they find body parts amusing. I recall years ago when a young relative went to the zoo with a video camera and took a few close-up shots of their cousins backside in between shots of the critters.
They all got a laugh out of it. Children don't change but their tools do. There is a problem with cell phones going on around this country.
Now children are passing around photos taken on their cell phones of themselves or others while not attired. Some kids have gone into locker rooms and taken pictures of unsuspecting kids only to then send the pictures to friends.
I have heard that these kids don't see anything wrong and find it amusing. Parents need to talk to their children about it and check their cell phones to be sure that they are not sending or receiving this kind of stuff. Some time ago I heard of a student who had received such a picture and he was arrested for possession.