This is actually one of the chow halls at my Army Basic Training regiment, the 2nd Battalion of the 39th Infantry. That flag is probably covering the tray conveyor window.
How do I know? Look at the chairs, our motto is: AAA-O, Anything, Anytime, Anywhere -- Bar Nothing. When we were in basic training most of us were annoyed by having to use it as a greeting (TRIPLE A OH SIR) but years later I looked into it and learned two things that made me change my mind about it:
- AAA-O is recognized as a Special Unit Designation, which means that not only it is official, but it can only be used by the 39th Infantry Regiment.
- Truth being stranger than fiction, the Germans in WWII were so impressed with the 39th that they assumed AAA-O designated shock troops and they had expected the Allied landings to be spearheaded by troops sporting the AAA-O on their helmets.