You could say something along the lines of:
"Hey, Friend, what's so good about weed? Why are you always smoking it?"
If he's smoking it for medical purposes, then just drop it, but if it's illegal and he's doing it to "look cool", then I would further ask questions about it.
The answer u r looking for is-B sweating, hope this helped :)
"You assure them that, as the parents, they are the appropriate decision makers for their baby and you will support their decision."
Occupational Health Handbook
