The shout comes from Cristiano Ronaldo's goal celebration, which he developed during his time at Real Madrid and popularised worldwide while playing for Portugal and later clubs. Ronaldo has explained that siu comes from the Spanish word for yes, and fans began copying the jump, turn and shout in stadiums and online. Clips of the celebration spread across YouTube, TikTok and football meme pages in the late 2010s and early 2020s, where extended versions became a reusable reaction sound for victories big and small.