Lookups spiked on January 22, 2011.
MSNBC host Keith Olbermann made a surprise announcement of his immediate departure after eight years on the network.
Numerous reports included the word mercurial, including The Baltimore Sun's television blog: "Keith Olbermann, the mercurial and controversial MSNBC host, announced on-air Friday night that he is leaving the cable channel immediately."
Mercurial means both "changing moods quickly and often" (as in "a mercurial personality") and "very lively and quick" (as in "a mercurial wit").
The word comes from the name of the Roman god Mercury, which was then used to name the liquid metal. It's likely that the sense meaning "quick" came from the speedy Roman god and the sense meaning "volatile" came from the behavior of the metal that bears his name.