According to the Zidane head-butt video on "Arsenal wtf"; the French Captain head-butted the Italian defender because he lingered on his breasts a little too long for comfort.
However, Zidane's agent said that Materazzi said something very very bad to him and that provoked the reaction. I don't know about that because the video doesn't show him saying much of anything.
Maybe he said Zidane was gay or a terrorist, I don't know.
Labels: Why Zidane butt Materazzi, Zidane Headbutt