bang [M16th] This is probably a Scandinavian word, which imitates the sound. The American expression bang for your buck, ‘value for money, return on your investment’, was originally used in the early 1950s of military spending, especially on nuclear weapons. The phrase bang on, meaning ‘exactly right, excellent’, originated in air force slang, and referred to dropping a bomb exactly on target. The Big Bang for the explosion in which the universe originated was originally a term of ridicule, used by the scientist Fred Hoyle (1915–2001) in 1949, but is now the standard term for a widely accepted theory.