@Cyran0 - Your post was very insightful, and it is exactly what I want to say to my friends.

At this point I think I've realized all of the risks involved here, whether beforehand or after talking to people here. I guess I sort of assumed everyone involved gave it the same kind of thought I did. But when we get together the next time, I'm taking it upon myself to talk about these risks and to make sure they understand what they're putting on the line. Physical health, integrity, the current status of our friendships, and future relationships being the main points.

I want them to be totally informed, because I doubt they even considered the possibility that down the line attraction or envy could result from this. Naturally I don't think it will happen, either. But I know it's very common in these situations, so it must be taken into perspective.

They probably thought about STDs, but dismissed the concern, like I did. But at least I know that if my health were in danger, I would have to alert someone, which means I'd have to spill the beans. I'm not sure anyone else thought about if they'd be willing to do that.

And of course they wouldn't think about how this would affect future relationships! That particular topic doesn't matter much to me personally, but I doubt the rest of them could say it doesn't matter to them.

I feel like I am armed with enough knowledge to make my own decisions, but the others might not be. So I believe it's my responsibility as their friend to discuss it with them, in case they don't realize the full magnitude of the situation.