Asswash Share definition Flag The toilet water that splashes in and around your ass when your poop lands in the toilet. Random Guy: "Ohh man, this burrito is gonna be the cause of some major Asswash in a few hours".Random Girl: "Ewwwww gross!?%$^!!". Asswash by eys cela May 17, 2011 0 0 Get merch Get the Asswash mug. Buy Now — $32.95 See more merch