Arse fax Share definition Flag When the label of underwear / pants sticks out over the seam of the pants. Uschi definately didn't look in the mirror when she left home, an arse fax was sticking out of her hotpants. Arse fax by Kid Stupid November 28, 2010 0 0 Get merch Get the Arse fax mug. Buy Now — $32.95 See more merch