And it's religious in nature... do you still tell them it's an urban legend?
... I added a comment to her wall that it was an urban legend with a Snopes link, and now some of her other friends are coming back at me and lecturing me on pointing it out, since it was "how everyone should act" and "it's a great story regardless".
... Should I just leave it alone because it's a sensitive subject?
Opinion seems to be divided about this, but the thing is - if the story is not true, then people are spreading lies. I for one would want to know if something I posted wasn't true, but a lot of people who pass around urban legends get their backs up when told it's not true. "We should still pass it on because people need to be warned!!!" and that kind of thing. Warned about stuff that doesn't happen or never happened? WHY??
So far, in the 15 years I've been teaching, the "Blue star acid tattoo" legend has surfaced about four times. The first time the principal printed it in the weekly school newsletter despite knowing it wasn't true. Her reasoning was the same - "It doesn't matter because parents need to be on the lookout." For what, fantasy objects?!! The second time (a few years later) it was being passed around with a notation to "tell the children about it". I sent it back to the teacher who had originated it saying, "It's not true - and I can provide proof if you're willing to wait until tomorrow." She was glad to hear it and withdrew the page. The next couple of times the principal just turfed it, knowing that I'd once again bring up the fact that it's NOT TRUE.
And just before the school closed last year, our PE teacher was passing around the "snake in the ball pit" legend. I went to all the teachers with small kids he'd shown it to and told them it wasn't the case - it's just an urban legend. They all seemed to realise that, yes, if it hasn't been in the paper, it's probably not true.
I think people need to be educated about urban legends and how to spot them. And NOT to pass them on. But others feel that telling someone their pet story isn't true is rude. I think spreading lies is ruder, myself.