Brendan Nyhan links to -- and mocks! -- this sensible argument by Leon Kass against eating in public:
...eating on the street -- even when undertaken, say, because one is between appointments and has no other time to eat -- displays ... [a] lack of self-control: It beckons enslavement to the belly. Hunger must be sated now; it cannot wait. Though the walking street eater still moves in the direction of his vision, he shows himself as a being led by his appetites. Lacking utensils for cutting and lifting to mouth, he will often be seen using his teeth for tearing off chewable portions, just like any animal. Eating on the run does not even allow the human way of enjoying one's food, for it is more like simple fueling; it is hard to savor or even to know what one is eating when the main point is to hurriedly fill the belly, now running on empty.
OK, Brendan, I'll concede that I have eaten ice cream cones and chocolate bars on public sidewalks. Eating or drinking anything while walking is a different matter. I've only done that under peer pressure, and I won't do it again. People will just have to copy those walking, talking, and consuming scenes from Law & Order and The West Wing without me. Kass is right: If you can eat something without feeling compelled to stop walking and taste it, either the food is not worthy of your stomach or you're not worthy of the food.
The sidewalk eaters are bad enough -- like people who walk and talk on cell phones, they do not move as fast as they think they do, and they always impede foot traffic -- but there are also the people who spread out full meals on their lap on the subway, and I've seen people eating breakfast sandwiches during a four-floor descent in my apartment building's elevator. (Oh, don't worry about dropping bits of food on the floor! I understand that you don't want you to get crumbs on your desk at work, or your own dining room table.)
I shall certainly meet these people in hell, so I will try to keep my distance in the meantime.
Below: One of a million YouTube videos by European tourists in ecstasy over hot dogs from street vendors in New York. Nothing wrong with a street hot dog -- just find a place out of the way where you can stand still and enjoy it.