fuckbaby Share definition Flag a slang term sometimes used to designate someone with whom one has a feeling of deep and natural affinity, friendship, love, intimacy, sexuality, and/or compatibility. "Mmmm....Fuckbaby," said Anthony to Katherine. fuckbaby by Eatt April 3, 2008 0 0 Get merch Get the fuckbaby mug. Buy Now — $32.95 See more merch