You'll probably get some GREAT replies on here and I won't steal any ideas I've seen previously. However, I do have an idea since he's slightly older than my own kids. I don't know how familiar with quantum physics you are, but basically, if he's interested in proving you're not his "real mom," he can reasonably more you're nothing more than a hologram and not a real mom!
There's a good copy of Scientific American on the shelves now. If he's looking for an alternate state of mind and relaxation, stimulating his left brain (not done often in schools of any sort) will definately make him feel high. (I'm pretty serious.) Also, rather than fighting about the definitition of "mom," I recommend for both your sakes doing something relaxing (which is why people smoke grass). I'm a fan of getting high off yoga. (You really do experience strange brain sensations.) Things like practicing headstands literally can turn a mood upside down! Fit TV has a show called "Breathing Space" at 2:30 and 5:30 EST. It's good for beginners and it will do both of you good.
I don't think you have a bad, subversive kid. Most teenagers are snippy and most smoke pot. While you don't like it, don't go into a panic. If either of the things I suggest work, let me know!