Mouthfunctioning Share definition Flag When your someone is nagging or whining too much. Jeff: I wanna talk to her but idk..... Jim: Damn Jeff quit your mouthfunctioning and just do it! Mouthfunctioning by bitchwithnoass October 3, 2008 0 0 Get merch Get the Mouthfunctioning mug. Buy Now — $32.95 See more merch