The phrase itself is informal British slang, with mate used as a familiar address and disgustin as a shortened, spoken form of disgusting. As a soundboard clip it circulates mainly as a short reaction sound rather than as a line tied to a widely identified film, show or song, which is why creators treat it as a standalone verdict. Its appeal comes from that flexibility: the same few seconds can judge food, gameplay, fashion or behaviour without needing an explanation, keeping it useful across meme edits, streams and social videos.