poosterbate Share definition Flag The act of performing self inflicted sex while in the process of voiding your bowels. i.e. Masturbating while you poop. Valma was using her phone on the meetme app but decided poosterbate instead. poosterbate by Valma DooDoo January 9, 2014 0 0 Get merch Get the poosterbate mug. Buy Now — $32.95 See more merch