To know the origin of "prendre son pied" (literally "take his foot"), we should not take this expression, which means "get a kick out of something", "having fun doing something", literally. Here, the "foot" refers to a measurement unit still widely used during the XIXth century. At the time, the foot, which measures about 30 cm, was used by pirates and thieves to share their booty. It was collected in a heap. After measuring the height, each one took up the equivalent of a "foot" of the treasure, objects or money stolen. Part of this amount was then spent for their pleasure in various activities (mainly prostitutes...). "Take his foot" was then generalized in the popular language. This unit of measurement is however still valid in aeronautics.