unfuckingbelievable Share definition Flag so unbelievable you have to add fucking for extra umph! .. my FAVORITE word .. UnFUCKINGbelievable! I would have never thought that drinking 18 beers could make anyone so hott! unfuckingbelievable by Errn April 8, 2003 0 0 Get merch Get the unfuckingbelievable mug. Buy Now — $32.95 See more merch