This sound comes from RPG Maker, the game-making software whose built-in effects have been reused in countless fan-made role-playing games. The poison effect was designed to play when a party member was afflicted, and its short bubbling tone became instantly familiar to players of those indie games. As gameplay clips and meme edits spread online, creators lifted the effect out of its original context and used it as a shorthand joke for anything toxic, sickening or badly chosen. Its retro, low-fidelity charm keeps it popular for nostalgic and comedic edits today.