Just back from the school run, and had a rather unfortunate experience in the car park....I was walking behind a woman who obviously felt she was wearing trousers, but in fact was wearing tights. Which weren't tight. And were see through - very see through. I could see her red and white stripey knickers very clearly through them. 
I was torn as to whether I should have said anything to her - there was a moment where she was on her own, with no other adults in earshot, and I could've gone over and had a quiet word in her ear. But I chickened out.
I mean, it it were me I would want to know. But I can't see how she didn't know - I always check my rear view in the mirror before I leave, but even if she doesn't then she must have seen how thin they were when she put them on, surely? I can't believe it was deliberate either, not with those pants. Or that arse.
So, WIBU to tell her if I get the opportunity again? Or should I just leave her to it?