Explaining Subway Behaviour to a Child

From the “City Room” at the New York Times:

Overheard on the subway:

Five-year-old to mother, referring to the people sitting across from her: “Why are they all so sad?”

Mom: “Oh, they’re not sad. That is just their subway face.”

I’ve often wondered what to call that special look people have on public transport. Now I know—it’s the “subway face”.