Puerta Troll circulated as a shared WhatsApp audio in Spanish speaking communities, where short prank clips are forwarded from chat to chat instead of coming from a film or show. The name simply joins puerta, meaning door, with troll, for the trick it plays on the listener. As WhatsApp audios spread to TikTok, YouTube Shorts and meme soundboards, the knock became a reusable reaction for fake visitors and interruptions. Its popularity comes from how ordinary it sounds, so the prank works in almost any language.