The ka-ching imitates the bell and drawer of mechanical cash registers that became standard in shops in the late nineteenth and early twentieth centuries, when a ringing bell signaled a sale being recorded. As an onomatopoeia, kaching, cha-ching and ka-ching have long been shorthand in cartoons and comedy for money changing hands. Online, creators use it much like a ding sound effect for instant emphasis, dropping it over sales, wins and expensive purchases because audiences recognize the register reference without any explanation or setup.