mofo-ing means: 1. Repeat the use of “motherfucker”, often while talking, usually shaking your leg, shucking, jiving, high fiving, or slapping your legs. Tracy is a Hollywood make-up artist in the comedy “Tracy Ullman In The Trailer Tails”, which was broadcast on HBO. Ruby does makeup for Debbie Reynolds, and tells her stories as she goes. She tells Pepper about Pepper, a black actress who used to have her make-up done to appear white. Pepper then recalls how she looked and acted black the last time they saw Pepper. Ruby offered her services to Pepper, but Pepper declined because Pepper is “openly” black and doesn’t need to make up for it to appear white. Ruby says “she Pepper was slapping her thighs and shaking her booty”….”high-fiving and mofo-ing”. (in Community Dictionary, added by Jaycee Briggs)