Well... Heard at weddings, in movie theaters and, of course, in football stadiums around the world and now in Tennis courts.

The sound of Cristiano Ronaldo's famous 'Siu' celebration became something of an unofficial soundtrack to 2021 -- and it's showing no signs of stopping in 2022.

So far, the crowd at this year's Australian Open has taken every opportunity to mimic the celebration in the stands, which has led to some confusion.

Multiple news outlets, commentators and even some players initially mistook the shouts of 'Siu' for boos, before eventually realizing what fans were actually shouting.

According to CNN, the chants have received mixed reviews from players, with home favorite Nick Kyrgios unsurprisingly relishing the boisterous support. After his opening round win over Liam Broady, the 26-year-old performed the 'Siu' celebration on court -- much to the delight of the fans
"I think it's like 'Siu' or something, what Ronaldo does when he scores," he added in his post-match press conference. "It was incredibly irritating."

CNN has reached out to the Australian Open for comment, but tournament organizers were not immediately available to respond.