It's my niece. I am really worried about her. she is a brilliat girl, always been good-natured, hard-working at school, a real pleasure to be around. She's sensible and always willing to help with my DC (her much younger cousins). In short, a lovely girl. She's also recently blossomed into a lovely-looking girl. Very pretty, very slim, very attractive.
So, cut to the problem. We all went on hols recently, her family and mine. She was borrowing my iPhone to go on Facebook as is usual for a teen. So far, so normal. She was telling me about what was going on on FB and in fact, a lad in the year above her, who she describes as the coolest boy in the school had started to exchange messages with her. She was THRILLED to bits. As we all know, things can be written electroically very easily that would be very hard to say face to face and within two weeks, this electronic relationship had gone from passing acquaintance in the school playground to full on, hot and heavy emails via FB.
(Full disclosure: some of the stuff she freely told me about, but 
I must admit to snooping a bit...when she returned the phone to me, she often forgot to log out of FB, so when I opened FB for my own use, there were all her exchanges).
I know she can't be a child forever or even very much longer, but, but.....
....the stuff this lad was posting
(a) on his own wall for all his friends to see was pretty horrible, crude jokes, he sounds sexist and arrogant
(b) privately to her - such as, "tell your mum you are going to the cinema, but get the 93 bus round to mine and we'll watch a DVD together cos my parents are away" made me shudder
My niece is very close to me and I would like to have a chat to her but what can I do to help explain that sometimes the Mad, Bad and Dangerous to Know ones are really just wankers and that getting involved with this lad has disaster written all over it? Without reinforcing his attractiveness to her and pushing her into his arms??