Quack Mouth Share definition Flag An incredibly offensive slur that should never be used. The definition of the term is so offensive it shouldn’t be discussed Gary: “Stacy is such a quack mouth”Ben: “Gary you seriously can’t say that, so uncool” Quack Mouth by FriendlyThesaurus March 13, 2021 0 0 Get merch Get the Quack Mouth mug. Buy Now — $32.95 See more merch