Cannabis isn't a drug: It's the plant; however, I think he meant to say THC, which is a drug, to which I would also say "You're joking, right?"
I have a slightly different situation: I never go to school high, but I often stay up until either twelve or three the night before (three hour intervals of sleep are believed to help people wake up, and it helps me); therefore, I can get up, not be tired and do well at school but my eyes are always bloodshot, and I swear at least one person in every single class says something similar to, "Dude, are you stoned or something?" It is so damn annoying.