NO NO NO! don't tell your friend's mother what she told your daughter. She's 18. She has been on social media awhile, like everyone her age. She can choose to do tinder and send pics if she wants. 27 isn't that much older than her. Mind your own business! Once she's in college, she'll have plenty of distractions from this activity. Doing stupid stuff is part of growing up. Confiding to a friend and having that confidence broken - that a darned nasty lesson. This activity doesn't sound dangerous. People send pics of themselves every day. Chill out.