I just wanted to say that their are many factors here that no one has mentioned.
Zidane is a first generation Frenchmen from Algerian (Muslim) decent (He describes himself as a non-practicing Muslim). After the last World Cup he won, he was referred to as an Algerian Frenchmen in the French press, which I understand to be a racial slur of sorts. Also, a politician in France had already said early in the Cup that the French team did not represent France, as 16 of the 23 members were non-Whites. Add to this that the Spanish and Italian leagues are known for racism. Like, when a black person is taking corners the crowd will make monkey noises and throw bananas at the player, for instance. Also, Zidane has had previous episodes of violence on the pitch because of racial slurs.
Pretty much, the Italian said something racist. Well, probably.
Personally, I think it is a cool way to end a career if it was a racial slur. I doubt he is too hot on France, especially because of how they treated him last time. Plus, he already has won a World Cup, which is more reason to stand up for yourself, etc. If it was a non-racist statement I guess he just lost his head. I would literally bet all of my posessions on it being a racial slur though.