The ka-ching effect is a widely recognized stock-style money sound built around the idea of an old cash register ringing open. Online, it spread because creators needed a fast audio cue for payment, sales, gambling wins and anything that implies profit. Search interest often clusters around terms like cash till sound effect, cha ching sound and venmo sound, even when the clip is used more as a comedic symbol than a realistic recording. Its staying power comes from being instantly understood across short edits, memes and reaction videos.