Safety First Ladies
Wired magazine provides a “how-to” guide to checking your drink for roofies:
Roofies [Rohypnol] were usually colorless but they were reformulated since February 1999, so that they turn blue in a drink to be noticed. Cautious spikers using the new version of Rohypnol can still serve them in blue tropical drinks so the color is disguised.
[GHB] usually is tasteless, but may be recognized at times by a salty aftertaste. GHB can be produced as a clear liquid, powder, or a tablet, but it is most commonly used as a liquid.
(photo from ginsnob)