firesex Share definition Flag 1. Steamy sex on a bed of hot coals. 2. An expletive similar to fuck! with no discernable meaning. 1. I had firesex last night. 2. Oh firesex! I got screwed over! firesex by Jimbob Lieberbush September 17, 2008 0 0 Get merch Get the firesex mug. Buy Now — $32.95 See more merch