The line comes from the 1980 comedy Airplane!, spoken by Leslie Nielsen as Dr. Rumack during a tense cockpit exchange that plays the disaster film completely straight. The gag depends on the pun between 'surely' and the name Shirley, and it became one of the film's most quoted jokes as Airplane! grew into a cult favourite on television and home video. Decades later, short clips and soundboards kept the exchange alive, because the dry delivery still works as a quick correction in reaction videos, edits and memes.