Synonymous with date-rape, rohypnol is a 'slow-down' drug that has a similar effect to alcohol on the minds' functioning. It also delays the transmittance of messages from the brain to the muscles, thus making the user weaker. It has been used by ravers in the late 80's and early nineties, and more recently, has been used to 'spike' unattended drinks of females (or sometimes males) on a night out. It slows down the mind to the point that the person barely knows they are gettign raped until after the effects have worn off.
Controversial group the prodigy included talk of rohypnol in thier song "babys' got a temper".