They could be victims of rape, because they don't know what happened - if anything. The drug has no taste, or odor and it causes amnesia. It also stated that for some young people, rohypno has become the drug of choice at a lot of parties - it's in the same category as marijuana. The audience is towards teenagers that are with the opposite sex or at parties. The purpose is to scare people and make sure they get there own cups and watch out because you never know what could happen.
Some people have a strange way of having fun.
At the perties I go to, if some dude is seen dropping anything in anyone's drink they get their ass kicked, outside of course. Peole that sick, and that desprite make me cringe.