pooiss Share definition Flag taking a poo while simultaneously taking a piss. "Pooiss" is the combination of both words. Yesterday, i saved so much time on the shitter, i was pooissing, it saved me 37 seconds. Yes! pooiss by loadednine November 23, 2006 0 0 Get merch Get the pooiss mug. Buy Now — $32.95 See more merch