Yikes, that is very scary.
We evidently have "black tar" heroin in our community -- no kids were found using it, but there was a drug bust. So there have been talks about that, etc. I find that scary.
I never did a blessed thing, and I'm not completely sure why.
Part of it is the whole "if you can't be a good example be a horrible warning" thing -- my dad smoked pot, and I didn't like that he smoked pot, at all. It took the "cool" bloom clean off of that rose.
Secondary element is that I've always, always, from when I was very small, had a major pushback response when I feel pressured or coerced. So I had an initial "eh" reaction to pot (plus cigarettes and acid), and then when I felt pushed that negative reaction was redoubled.
Many of the friends who offered me those things went on to harder drugs but not in front of me. I went to many parties where the air was thick with pot smoke (so I'm not sure it's accurate to say I've never done anything at all, I probably got a mild high just from breathing), but the harder stuff was done in bathrooms and I wasn't invited. That was fine with me. I didn't like how my friends acted when they were on drugs.
They didn't really, either, though, so that was another element. I became known as the one who just plain didn't do anything, and eventually I got a lot of respect for that. Several of my friends had serious substance abuse problems (mostly alcohol, some harder stuff), and they moved from "come on, try it" to "you're so smart to stay away from this stuff -- stay strong, don't start." So that helped keep me away.
I hope my kid doesn't do anything, including pot. I don't like smoke. Pot brownies would be OK-ish (in the sense of I don't want her to but if she's going to, I'd much prefer that to actually smoking). But I definitely go the "open communication" route on this. I'd rather she be safe than just leaving it at "don't do anything," period. (She had a DARE thing at school and brought the booklet home, it was way too simplistic/ alarmist, I did some major critiques and we had a good talk.)