jfab Share definition Flag Jfab is an acronym for "just fuckin around bitch." It is often used to show how truly obnoxious you are. Person 1: "I love your sweater! It's adorable." Person 2: "Gee, thanks!" Person 1: "JFAB!" jfab by Wmialil April 8, 2011 0 0 Get merch Get the jfab mug. Buy Now — $32.95 See more merch