The phrase comes from everyday French slang, where je m'en fous is a blunt, familiar way of saying I don't care, and aussi adds the reply-like twist of me too. Written in chats as jmen fou, osef and menfou, this shortened spelling helped it circulate as a quick reaction among French-speaking users online. It is now shared as a short audio response in group chats and meme edits, used when someone wants to match another person's indifference or close a topic without starting an argument.