The implications to be drawn from the final panel might more than a little nasty, perhaps even gratuitously nasty, but I have it on the authority from someone with inside knowledge of the relevant sub-culture that it is indeed a thing.
(Click on the image for larger size.
Gnosis Transformations: Chapter Four, Page Twenty written and commissioned by Dr. Faustus of EroticMadScience.com and drawn by Lon Ryden is published under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.)