F.D.L.B. Share definition Flag An acronym that stand for Fat, Dumb, Lazy, Bitch. Me: Is she going to do anything to day. Coworker: No she is a F.D.L.B. I hope the boss fires her. F.D.L.B. by krusty's komedy klassics December 13, 2010 0 0 Get merch Get the F.D.L.B. mug. Buy Now — $32.95 See more merch