This cue comes from the trainer encounter moments in Pokémon Red, Blue, and Yellow, often abbreviated as Pokémon RBY, on the Game Boy. The brief chiptune alert became memorable because players heard it every time an NPC trainer locked eyes with them before a battle. Online, it spread through gaming edits, reaction clips, and short memes as a shorthand for “you've been seen” or “trouble is starting.” It still works well because its retro sound is instantly readable, even to viewers who never played the originals.