Rohypnol was used by ravers in the late 80's and early 90’s, and more recently, has been used to 'spike' unattended drinks of females (or sometimes males) on a night out.
Viagra is something that men use to increase sexual pleasure and the ability to achieve an erection.
Viagranol is a proposed blend of the two drugs – primarily used by ugly people to get laid by men they fancy – sufficiently slowing down the mind of the victim to the point that the person barely knows what’s going on to start with.
At this point, the Viagra aspect kicks in and ensures lengthy erections for the victim which the perpetrator ‘enjoys’.
Fuck, I SO fancied him but he wasn't interested. After I popped a Viagranol in his beer, he was banging my brains out for hours before he knew it!