When railing a girl doggy style a man places two fingers in the females asshole. Once the fingers are inserted into the asshole the male attempts to use those fingers to masturbate himself through her asshole. The name is mixture of defication and masturbation.
Man I tried to give her the duffication but when I tried to get that second finger in she got pissed.
by Duffman81221 January 03, 2014