Fanshash Share definition Flag Code word girls use for a rash on their vagina. Used when there are lots of people around so they don't draw attention to themselves when they are informing people. "I have a really bad fanshash.""ew.""Get some cream for that or it'll start to smell." Fanshash by Bantz June 16, 2012 0 0 Get merch Get the Fanshash mug. Buy Now — $32.95 See more merch