The act of "pooping" in a bandanna and slapping someone in the face with it.
"Dude you should have been there i gave a dirty poncho last night!"
by Roidz December 06, 2006
the act of shitting (preferably diarrhea) on ones head; therfore leaving the person with a "dirty poncho"
guy: "I just gave my girlfriend a dirty poncho."
by sirsmokebudzalot August 30, 2011