I once had to save a kid who was online from someone who was trying to mess with the kids privates in a role play type of way on a public post. I can't even use Google+ (it's getting deleted in April thank goodness I have so much trauma from there) without wanting to throw up.
I used to chat on IRC, and had the opposite problem. The people wanted to talk about fattening up their kids. That was so wrong, and I would stop chatting with that person.