If you were in downtown Denver, it likely would have been a marijuana pipe. I was there before the law changed and I practically got a contact high just walking down the street. Although my at the time 13 year old daughter was with me, there was a silver lining to seeing people smoke pot openly in downtown Denver. The people doing it were living and breathing advertisements for not being career pot smokers.
Lest anyone be offended by my comments, I honestly don't care what substances adults use (hell, I tried them all in my 20s and I still love beer). But as a parent, I'm keen on keeping my kids away from intoxicants until they reach the age of majority. Is it hypocritical of me? Nope. Science supports me in that a developing teen brain is much different than a fully formed adult brain. Not a good idea to monkey with your body's most important organ before it has finished growing and developing.
Other than that, I'm honest with my kids about vaping, smoking and drugs. I believe in giving them age appropriate and truthful information. Lying to them will only erode their trust in my dad wisdom.