mash her gash Share definition Flag Term used to describe the act of hardcore/rampant penetrative vaginal sex. 1. "Oi Farmer... I wanna mash your gash!" 2. "I'd well mash her gash" mash her gash by hotsweetpanini December 19, 2007 0 0 Get merch Get the mash her gash mug. Buy Now — $32.95 See more merch