The ka-ching sound is a widely recognized stock-style money effect based on the noise of old cash registers opening and ringing. It has been used for years across radio, television, games, mobile apps, and internet memes as a shorthand for money, sales, and rewards. Online, creators still use it because the meaning is instantly clear even in very short edits. It often appears alongside other quick reaction effects such as a ding sound effect when a joke or visual needs an extra payoff.