[nicoburns]

> I’d like to know the words that might stop kids even giving a try once.

Just be honest about the risks of different drugs, rather than making a big deal out of drugs like cannabis or mdma that are not particularly harmful (and that there's a good chance they will know are not particularly harmful because all their friends are taking them).

Kids will listen to you because they respect your opinion, not because you say particular words. So make sure that your opinion is worthy of respect, and matches up with their experiences.