Good thing about living in Arkansas is that there's no in-state pro teams you feel obligated to support. Most people are Cowboys fans and that may be why I can't stand them. I don't know. Anyway, my dad was one of those who just picked a city/area and chose all of those teams as his favorite. Don't know why he went with the Baltimore/D.C. area but he is/was a Colts, Bullets, and Orioles fan. I guess you could say I jumped on the bandwagon during the 1995 season when they lost to the Steelers in the AFC Championship game.
Getting Peyton Manning a few years later obviously helped me stay loyal. I definitely won't be even a little upset if he wins another Super Bowl with the Broncos, unless they beat the Colts on their way. And even then I'll probably be able to get over it semi-quick like I did last year when the Thunder got beat by the Mavs in the WCF, because I've always wanted to see Dirk win a ring.
Cincinnati Bengals. Grew up about 2 hours from Cincinnati, and was a Reds fan from birth practically, so it made sense for me to follow the local football team as well. It's been a brutally difficult ride to say the least, but I watch every Sunday, and love my team through thin and thin.