If you hope somebody Breaks A Leg you are sending them a message of goodwill and good luck. The expression is usually reserved for a stage actor or musician prior to a performance. Some people have claimed that the expression originates from the assassination of Abraham Lincoln, shot dead in his private box at Ford's Theater in Washington DC, on 14 April 1865. His murderer John Wilkes Booth, a renowned Shakespearean actor, broke his leg when he jumped down to the stage in order to make his escape. It’s been claimed that the saying arose as a form of black humour. In fact the phrase was common centuries before this event, when a measure of the success of a stage performance was the number of times an audience called the performers back to the front of the stage for applause. Every time the curtain was reopened the actors bowed, and the more often this happened the greater the chance of “breaking a leg”.