Lookups spiked on February 7, 2011 - the day after the Super Bowl.
During her rendition of the national anthem that preceded the game, Christina Aguilera botched the lyrics and never sang the words "O'er the ramparts we watched / Were so gallantly streaming." She instead improvised a line that closely resembled a previous line in the song ("What so proudly we hailed / At the twilight's last gleaming").
A rampart is a wall that is built to protect a castle, fort, or city. Francis Scott Key, who wrote the poem that became the "Star-Spangled Banner," was observing the British attack on Fort McHenry during the Battle of Baltimore in 1814 when he wrote the famous words.
Rampart comes from the Middle French word meaning "to protect" or "to defend."
Photo credit: Nick Step / flickr