Having completely written an entire paper, looking up the final citation that's supposed to blow away my readers with my brilliance (and finally swing an A from a professor who always gives me Cs)...
And discovering that I overlooked one single sentence fragment in the story ("their old debate, and indeed the only debate that ever happened in their country") that completely (and I mean completely) destroys my main support for my thesis. Fourteen words out of like a hundred pages and a third of my paper's trashed.
