Going uptown, the F train was packed. With my back to the doors, I stood, studying people’s footwear. A baby wailed. Some teenage girls chittered like squirrels. A garlicky dude was barking into his cell phone.

Across the way, an older man faced outward, his nose pressed to the glass, grocery bags swaying at his sides. As we hurtled through the dark tunnel, he cried out:

“Oh, there they are”—everyone else on the train got quiet—“those teenage mutant ninja turtles. Workin’ on the tracks.”

I smiled as we rode on in silence.