Being from the Bay Area, at many times in one's life, there comes a time to choose sides. When it comes to the local sports teams, if you weren't either directly born in San Francisco or Oakland or live there currently, you would find in school, work, even home, you would have to decide where your loyalties lie...and be prepared to stand and defend your home team.
SF loyalists support the Giants and 49ers, while Oakland natives back the A's and the Raiders.
SF loyalists support the Giants and 49ers, while Oakland natives back the A's and the Raiders.
People who are not originally from the Bay can sometimes neglect to understand how serious this rivalry is. For instance, everyone knows there is no fans more fiercely loyal than Oakland's Raider Nation. We saw the most fan violence ever during the Niners vs. Raiders home game at Candlestick during the 2011-2012 season. The emotion of supporting your team fueled with alcohol and testosterone...well, we all saw the results.
Bay Area people, like most around the country, are fiercely loyal to our home teams. The issue is that we have multiple to choose from, many people end up being transplants around the bay, so where a particular Nor Cal-ian's loyaties lie is not as clear as it would seem.

I am of the opinion that most people in the Bay think that way, but then you will always get the odd support of New England (Patriots) or the Lakers. And with South Bay native Jeremy Lin becoming an overnight celebrity on the Knicks, we might pick up a few straggling Bay Knicks supporters as well.
As versus Giants...Raiders versus Niners...Warriors versus Sacramento Kings or Lakers...
Are you are Bay Area loyalist?