Folks at @BlackHatEvents and @defcon - watch your drinks. Years ago I was rufied at a Vegas conference. I was lucky, I just lost a phone, money, and time canceling credit cards. This isn't just something women have to worry about, it's in everyone's threat model. Be vigilant.
Also, many people enjoy roofies- why waste them on someone who do not want it? Is the theory that it is done because of sadistic enjoyment of endagering other people? I have a hard time beleiving that so many people are sick in that way it really is sometjhing to worry about....