I believe that it's a reference to the colloquialism that references how matadors use red capes to fight bulls: https://www.urbandictionary.com/define.php?term

I believe that it's a reference to the colloquialism that references how matadors use red capes to fight bulls: https://www.urbandictionary.com/define.php?term=seeing%20red https://www.urbandictionary.com/define.php?term=seeing%20red So Team Red -> Seeing Red -> Bull?