I knew some of the people there, so it may not have been sex related. I was never unconscious. Luckily I went with a friend who drove. On the ride home, the road kept changing. So I knew it was not booze or even LSD. And it lasted for the next two days.
My guess is there was someone there who really disliked me, or, just as likely, it was just a random spiking of drinks.