Ronaldo made the Siuuu his trademark celebration during his career at the top of world football, jumping, turning in the air and shouting the word as he landed after scoring. Fans soon copied it in stadiums, and clips of the celebration spread across social media, football games and meme videos, turning a personal ritual into a shared chant. It remains popular because it is short, instantly recognisable and tied to one of the sport's most famous players, so it works as shorthand for confidence and success.