Thanks for all the various replies! I'll give you a little more detail. Basically this girl used to be friends with my friend's DD, but they aren't anymore. I think she told me this to get my DD's friend in trouble,
knowing I'd probably tell my friend the whole story.
So I called my friend just to feel her out a bit over it and as soon as I mentioned this girl's name, my friend blurted out, "
Don't believe a word out of that girl's mouth, she's a pathological liar!" Well, that did it for me, so I didn't say anything. Plus, I know that my friend is extremely vigilant with her DD and they spend a lot of time together. My friend would recognize the signs if her DD were high.
Oh the drama of teenagers!

I barely survived my own teen years, how am I going to get through my own kids'?
As for rumors, I definitely have first hand knowledge of them. My life was torn apart by rumors, and they completely ruined my relationship with my mother. When I was a kid, something pretty bad happened to me (you can probably guess). The boys involved told all their friends, only the story was twisted to make me a willing and active participant. One of my mother's friends got wind of the twisted version and told my mother. My mother, not being a reasonable or rational person, made my life a living hell for many years.
Because of that, I wouldn't make a decision like this lightly.