colossal fuckup Share definition Flag basically when you had fucked up but to a much great extent. Person 1: Dude my dog shitted all over the neighbor's yard Person 2: now that's a colossal fuckup colossal fuckup by KarateMachinery August 16, 2018 0 0 Get merch Get the colossal fuckup mug. Buy Now — $32.95 See more merch