I had that happen during my senior trip in high school. Long story short, my art teacher at the time was at the beach the same time us seniors were and invited us to come and drink at his hotel. Several of us had our drinks "roofied," and no one has any recollection of the night. Luckily I had my best guy friend there to help me, and I only woke up with a black eye-- who knows from what. It was scary as hell (the teacher came back and "resigned"). After that, I always watched my drinks and never had another problem with it. Extra vigilance is key!