'Fi duma égua' is Brazilian slang, a shortened spoken form of 'filho de uma égua', used as a rough, teasing insult among friends. As an internet sound, it circulates as a user-uploaded voice clip with no single documented original video, shared through meme soundboards and short-form edits. Its appeal comes from the rhythm of the phrase and the confrontational delivery, which fits gaming rage compilations, football banter and betrayal memes. Because the insult is playful rather than formal, creators keep reusing it as a quick verbal punchline.