And those girls are obviously high school teenagers. WTF happens to people when they get old that makes them forget how they talked, acted, and looked at 16? Even if you didn't, you sat at a lunch table alone observing all the social 16 year olds acting talking, and looking this way.
You owe your children enough not to forget what you were doing at key times like this in your life so that instead of being shocked by their actions and lecturing, you understand them enough to discuss what may go on with them and help them come up with sound decisions. If you're surprised by how these 16 year olds look and act, your daughter will be doing the same by age 11 behind your back because you've separated yourself from reality and are oblivious to the world.