The act of wiping period blood across the upper lip of a woman post-intercourse or phalangal pleasuring of the vagina with a penis or finger(s) during her menstrual cycle.

Similar to the 'Dirty Sanchez.'
Friend 1: "Man, my girl didn't tell me she was on the rag, so when I pulled out and saw what was up, I gave her a nasty Dirty Dahmer!"

Friend 2: "Dude, you're disgusting."

Friend 1: "Hey, it's not my fault! If she would've told me her vagina was a crime scene this never would've happened."
by HLoVE December 28, 2010
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