The sound comes from the Pokemon video game series, where stepping into tall grass or a cave can trigger a random battle with a wild creature. That encounter cue became familiar to players through years of handheld and console games, and clips of it later spread to video edits and soundboards detached from gameplay. Online, creators borrowed the dinger as shorthand for any surprise appearance, treating everyday people and animals as if a battle were about to start, which keeps the short effect in regular meme use.