Being born-and-raised in MA now living in Southie, and in spite of Southie being gentrified a great deal as of late, I still would make sure any of my friends from outside of the city don't wear Yankees gear or say anything bad about the Sox. Or Lakers, or Canadiens - it's also fascinating that the biggest sports rivalries in the major sports in the US all seem to stem out from Boston as a whole.

And yet, as crazy as these rivalries seem, it pales in comparison to soccer rivalries like Arsenal/Manchester United, Real Madrid/Barcelona, or AC Milan/Inter Milan. People are dying at these games.