<P> To "break a leg" is archaic slang for bowing or curtsying; placing one foot behind the other and bending at the knee "breaks" the line of the leg . In theatre, pleased audiences may applaud for an extended time allowing the cast to take multiple curtain calls, bowing to the audience . </P> <P> Related to this, some argue the mechanism for raising and lowering the curtain was controlled by a crank arm' leg' . Therefore for popular performers, continued curtain calls may result in a broken crank arm . </P> <P> In the time of Ancient Greece, people didn't clap . Instead, they stomped for their appreciation and if they stomped long enough, they would break a leg . Or, some would have it that the term originated during Elizabethan times when, instead of applause the audience would bang their chairs on the ground--and if they liked it enough, the leg of the chair would break . </P> <P> Some etymologists believe it to be an adaptation from the Yiddish translation into German . The phrase "Hatsloche un Broche" (הצלחה און ברכה) ("success and blessing") had been calqued from the German phrase "Hals - und Beinbruch" ("neck and leg fracture"), because of its similar pronunciation . The autobiography of Manfred von Richthofen records pilots of the German air force during the First World War as using the phrase "Hals - und Beinbruch" (neck and leg fracture) to wish each other luck before a flight . The phrase is now most typically used to wish an actor good luck before a performance, or a student good luck before an exam . </P>

Where does the expression break a leg come from