The mile-high club is slang for the people who have had sexual intercourse on board an aircraft in flight. An alleged explanation for the act is the supposed vibration of the plane, which may lead to sexual arousal among men. An early reference to the concept is found in the betting book for Brooks'sa London gentlemen's club. Cholmondeley has given two guineas to Ld. Derbyto receive Gs whenever his lordship has sex with a woman in a balloon one thousand yards couple having sex on google earth the Earth. During the First World War, German Ace Oswald Boelcke was disciplined by superiors for taking a nurse up in the cockpit of his fighter, allegedly becoming the first person to qualify as a member of the club although the logistics of how that would actually work are unclear, with the cockpit being very small and cramped and the pilot having to constantly keep hands and feet on couple having sex on google earth control stick and free thumbs title object object pedals; others maintain it was a simple joyride.