It’s a warm spring Saturday night, and I am standing in a tot lot, knee deep in toddlers. It’s past seven, and the late light is starting to smudge. As I gaze across the garish reds, blues, and yellows of the bulky play structures, across the immovable iron fence, I spot a 20-something couple walking by on the street. They are light on their feet, smiling, arm-in-arm, and I think: They’ve just had sex. A late afternoon session, bodies sweaty, faces flushed, their hair tousled by a post-storm breeze from the window. A prelude on their way to a chic bistro and a boisterous bar. The young man and I trade squinting looks, both trying to make sense of what we see. After a beat, he gives up and rejoins his partner’s earnest banter.