There are many things some people say about Rohypnol that are fake (e.g. not allowing pregnancy), it even used to be a spam email for a long time on the internetz, "ZOMG CAUTION THERE ARE RAPIST'S USING ROHYPNOL, rohypnol is a pill that make u sleep then they rap u and u cant hav childrens forevah afte takin this pill", none of these are real (although the first part can be) but the pill itself does exist [link], it's a pill for sleeping, and should only be used after prescription.