In Chicago you can drink (non-alcoholic of course) and eat on the
subway and buses as much as you want. However, I realize now why DC
forbids it. Today I brought a coke onto the bus and opened it, not
realizing it had apparently been jostled upon delivery prior to my
purchasing it or something like that. I certainly didn't shake it or
anything. So when I opened it it spurted out everywhere on the bus,
soaking the floor, etc.,just as people were getting on. It was just a
little embarrassing, to say the least. But seriously my first thought
was, so THAT'S why they don't allow drinks on the DC metro!