Our fans, and all the other fans, use the same tune. For example, our fans often sing to Seba "Uno di noi, Giovinco uno di noi" and it's the same tune as "Come la Juve, voi siete come la Juve". But Badass doesn't understand one single word in Italian and for some reason he thought all the fans say the same thing.
P.S: On the other hand, he said he's singing together with the Juve fans. What exactly is he singing?