The shout comes from Cristiano Ronaldo, one of football's most recognisable players, who turned Siu into his signature celebration after scoring. The move, a jump, mid-air turn and powerful landing, is almost always accompanied by the shouted word, which comes from the Spanish word for yes. Broadcast clips, fan compilations and social media edits carried it far beyond football stadiums, and it became a shorthand for confidence and victory in memes and short videos. Years later it remains instantly recognisable, even to people who rarely watch a match.