When:
Lookups spiked on June 6, 2011.
Why:
In the scandal involving Congressman Anthony Weiner, the word was frequently used to describe the content of his tweets.
For example, according to a New York Times headline: "Weiner Admits He Sent Lewd Photos."
Lewd means "obscene" or "vulgar," and comes from an Old English word for "ignorant."
Love words? Need even more definitions?
Merriam-Webster unabridged