When:
Lookups spiked on June 12, 2012.
Why:
The word was widely used in commentaries about President Obama's remark that the private sector is "doing fine."
For example, according to a headline from The Atlantic, "Romney Finally Has an Obama Gaffe He Can Work With."
Gaffe means "a mistake made in a social situation" or "a noticeable mistake."
In French, gaffe originally meant "boat hook." Sailors' slang for the mistakes of inexperienced shipmates probably evolved into the word's current meaning.