Jiayou, literally translated as add oil, is a long-established Mandarin Chinese expression of encouragement, used for generations at school events, sports competitions and public performances. Its use spread well beyond China through Chinese-language social media, international sports broadcasts and gaming streams, where short, energetic cheers travel easily between languages. Online, the single shouted word works as a compact, instantly recognisable signal of support, even for viewers who do not speak Mandarin. That simplicity, combined with its positive, team-spirit feeling, keeps it useful for creators cheering on friends, players and underdogs.