yeah dude if he caught you talking or writing about it he could report it which would essentially influence the campus police to conduct an investigation, I.E search your car, backpack, and locker but as long as your smart and you don't have any illicit drugs on you then your completely fine. Talking about drugs is backed by freedom of speech so they couldn't even file it on your personal record unless they found something on you and if they did file it you could easily say you were writing a hypothetical situation or discussing one.