And they are showing it by rioting complete with burning mattress's, blocking public thorough fares, and gathering in a generally aggressive fashion.

 I have always thought that rioting due to something sports related sounded like a real hoot, the only problem is that both of the team's that I would possibly riot because of have stadiums' located in very dangerous hoods - Oakland and San Francisco respectively.  Both are definitely places that you don't want to be running around at night without a good working knowledge of where you are geographically (and a hood pass - which i have oddly never been offered) when you have to run from the cops and their tear gas and rubber bullets etc.  I am a pretty tough guy for the suburbs - but in the hood it is a bit of a different story.  That being said  I would totally riot in a college town.  College towns are above and beyond the best places to get wild in the streets, the setting is hell of nice with the brick buildings, trees, and what not, plus there are plenty of those shitty dorm mattresses that ignite quickly.  Also not to be overlooked is the fact that the majority of towns that colleges are located in do not have very sophisticated riot police.  Now of course I am not saying that I think that destruction of private property or violence against people is OK, but I am not gonna get all huffy about a couple of burned mattresses and an over turned cop car or two.  Fan's put so much of their time, money, and emotion's into rooting for their sports' teams and if they want to blow off a little steam after a seminal moment in their team's history I say have at it...just don't hurt anybody or cause too much damage.  I propose team's in the major sports create "riot zones" that are basically large fenced in areas where fans can tear down pre-fabricated structures and maybe bash up cars that are brought in from a local junkyard.  I think this would satiate the worries of local politicians, and most importantly create a safe and manageable riot area so people can go crazy without things getting out of hand.