use the bit about teenagers and reverse psychology, tell them that however much they know about teenagers and drugs, what makes them get into it in the first place. rebellion against the priciples your elders stand for. that inlcudes doing things you are not supposed to do, i.e. "illegal" drugs, alcohol, tobacco, its natural, i am doing it right now and loving it. try to get them to admit that the more they try to keep you from using, the more likely you will use and maybe even get into "hard" drugs although i dont give a shit, but try it out.