Joking aside, I told him what I would tell anybody, and that is what your mom does or doesn't do is irrelevant to the choices you make, as we are 100% responsible for our choices. She could wake up and smoke a 9-inch blunt and still have every right to demand that you do not smoke pot while living in her house or while driving around. I told him that instead of focusing so much on what mom and others do, focus on YOUR life and what YOU are doing. Find a purpose. Find something productive to do. And if you are so "okay", why can't you stop? I told him that he is using his mom drinking wine as an excuse to smoke pot, which in his mind, somehow minimizes "just smoking pot." And if none of those arguments make any sense, have a gander at what you look like sucking on a thick tube and see if that makes sense.
The best was that he said she should have to stop drinking wine if he has to stop smoking pot, that it's only fair. Look, besides being totally full of shit, he actually seemed like a nice kid. But sorry, you're never going to get me to validate that kind of thinking. And no, I don't feel bad for you. I feel bad for your mom. Also, don't tell your mom what to do, kiddo. One day you will realize how inappropriate that is... one day if and when you finally begin to grow up.
Also see: Pot