F.O.G. Share definition Flag Fucking old guy. The old men who always creep on tounger women, like they actually have a chance. "That F.O.G. keeps creepin on me" "I just hit that F.O.G.'s Mini VAn" F.O.G. by queeney December 3, 2007 0 0 Get merch Get the F.O.G. mug. Buy Now — $32.95 See more merch