So then I’d imagine, @Pinkyyy, that if your children do consider experimenting with drugs, that the last thing they’re going to think of doing is asking for your advice or guidance. Your approach is your choice, and I hope (genuinely) that works out well for you. I don’t see why you are so outraged at someone taking a different approach, though.
@MrsMercurio car journeys are conducive to the best conversations, ime - non confrontational situation, seated side by side with no forced eye contact, natural pauses as driving, things to look at outside the car to diffuse the intensity... all perfect for chatting with teens or kids. 
I’ve never gone for the ‘you must never do this’ approach with drugs - ultimately, I don’t think it works, and I think it’s her body and her choice, when it comes right down to it. What I have always done and will continue to do, though, is try to give a balanced and truthful picture, encourage her to think for herself and weigh up the risks with the benefits, and be as safe and savvy as possible if she does decide to intoxicate herself (I include alcohol in that, btw). I’d always rather she asked my advice/input on something than felt she had to hide things from me.
Good luck with your boy on Saturday.