The phrase is Brazilian Portuguese slang, with vc short for você and cocô meaning poop, giving the line its childish insult tone online. Short voice notes like this spread through WhatsApp audios and soundboards, where users save the funniest out of context threats to reuse in other conversations. Its popularity comes from how reusable the fake anger is, letting people drop the vc e um coco e eu vou te matar sound into arguments, game chats and meme edits without meaning it seriously.