Another option would be to not engage in illegal activity with your students, creepy or not. Look kids will be kids, and booze, drugs and sex will always be at the top of their to do list. This doesn't mean that it's okay for a professor to participate in this with his/her student. I'm sure you had a good time, and I trust your judgement on whether or not something else was going on, but horribly unprofessional on his part. How would the parents have reacted?
A highschool teacher's relationship with their students shouldn't include drinking, drugs, porno, strip clubs, or any other illegal activity. It isn't their place to decide what is appropriate and whose mature enough to handle it. It also compromises their authority and ability to do their job. IMO, alot changes when somebody goes to college. An individual is becoming alot more self-sufficient and the professor student relationship is different.