Mo Deff Share definition Flag Most Definetley: a saying that means most definetley. use when you are drunk,stoned or on the verge of pukeing. Guy1:hey dude you wanna go party? Guy2:Mo Deff man! Mo Deff! Mo Deff by Garrett Silva May 5, 2005 0 0 Get merch Get the Mo Deff mug. Buy Now — $32.95 See more merch
