I'm a TN alum from MD, moved back up to DC for work after graduating. It's true that the football sucks up here compared to down there, but be careful when you talk smack to Terps fans (remember, they did beat us pretty badly in the Peach Bowl a few New Years Eve's ago).
DC has a bar called Blackfinn that is a designated TN Volunteers bar where many TN alum meet up for football games: BlackFinn American Saloon
. I was skeptical to give it a shot, but after my first experience there I was sold. The place is basically dressed in orange for TN games, they turn off most music to put the TN commentators on loud audio, and at least 50 TN fans have been there each time I've gone. They even blast Rocky Top after touchdowns.