get a big sign that says" mom, dad, i use drugs". not really but i did have a poster of that when i was in high school.

i just told them when i made a comment one day about something in a health foodstore that smelled like pot and my mom asked how i new that. cant say she was happy about it but i said that at least its not crack. but i also support my own family and work 50-60 hours aweek and dont let it interefer with whats imporant. so even tho i smoke a little grass im a responsible adult.
the best thing to do is just show them you are a responsible person then let them know