Mankrob
a Mankrob is the act of placing your stretched out anus over the penis of a somehow unsuspecting male (perhaps sleeping nude, or drunk and has been undressed.) It is a mankrob regardless of whether orgasm is achieved, although there is a certain element of emphasis on the orgasm of the victim.
sleeping peacefully on the couch, Kyle had no idea David had pulled out his schlong and Mankrobbed him until it was too late.