coullion Share definition Flag Cajun French noun. Literal translation = Testicle. Pronounced coo'yawn. Someone who is a coullion is "a nut," i.e, a crazy person. Pooyie! Dat Boudreaux is a coullion. coullion by Pinchdatail August 30, 2007 0 0 Get merch Get the coullion mug. Buy Now — $32.95 See more merch