Sex act in the same realm of the "Dirty Sanchez" and other named acts/descriptions. A sexual act that occurs when a couple is engaged in doggy style sex. The male inserts his thumb into the anus of the female during vaginal intercourse. When she turns her head around to see what happened, he makes a poop thumbprint on her forehead.
"I was so into it when he was fucking me from behind that I barely noticed his thumb in my ass. When I turned around to ask him to fuck me harder, he gave me the dirty thumbprint."
by RHGF04 July 18, 2006