Many Brazilians are uneducated bastards that don't know where to stop, and I say that as a brazilian. You can't expect logic in the brazilian behavior in situations like that, specially when they are drunk. Trust me, I see a lot of brazilians using Argentina shirts with Messi written on the back on the streets everyday (it's not a world cup phenomena), or Barça kits with Messi instead of Neymar. Lots of Corinthianos dream with the return of Carlitos and Marcherano; Dalessandro is an Idol on Internacional, like many other argentines became idols in brazilian clubs. Brazilians love what we call "raça argentina", when the players play with their hearts, never giving up during the matches. If it was Argentina losing by 7 instead of Brazil, the players wold have kept their heads up, the supporters would still be singing, while brazilians were devastated and booing our team. So there's this secret admiration and even some envyness. But you know, we're too proud to assume it.
But there's this rivalry, and from time to time we receive informations of a argentine broadcaster calling brazilians of 'macaquitos', the "Olé" newspaper always with provocative headlines against us, and some people try to retaliate.
On the other hand, the brazilian broadcasters tend to reinforce this rivalry just for the audience. There's one that says "Winning is good. Beating Argentina is even better!"
It's part of the fun, I guess. Don't take it so seriously. Brazilians have low self esteem. That's why they do this kind of things.
