What is Ronaldo's Sii celebration all about? When Ronaldo scores a goal, he usually jumps into the air, turns around his body, and opens his hands in a style known as the'siii' celebration. As a result, the iconic "Sii" celebration was born during a match against former Premier League rivals Chelsea. "Well, I was in the US and we played against Chelsea, and I don't know where it came from," Ronaldo recalled. I just scored and exclaimed,'sii!' "To be honest, it was natural. "I started doing it after that, and I feel like the fans, when they see me, they're like'sii,' and I was like, 'wow, people remember Cristiano because of the sii,' so I kept doing it.".