This fan couldn't decide which Beltway team to cheer for, so he wore a jersey for both

In relative terms, the Battle of the Beltways is a new rivalry with the Nationals bringing baseball back to Washington, D.C., in 2005. Perhaps because the rivalry is so young or because the Orioles and Nationals play in different leagues, it hasn't yet grown into the sort of passion and intensity that defines, say, the Yankees-Red Sox or Cubs-Cardinals rivalries.
That lack of pure antagonism between the Orioles and Nationals made it possible for this fan to unabashedly declare his allegiance to the Beltway:

While we can't provide a genealogy of this jersey, we can say for sure that he was set up to leave Camden Yards happy regardless of the outcome of the game.
Despite the jersey's ambiguity regarding his rooting interests, this fan's hat suggests a slight preference for the Orioles. In which case, he went home even happier than he may have otherwise as the home team took the series opener 6-4.