I once worked in an office where the guy who sat in the cubicle beside mine, so that we were separated by a flimsy wall that didn’t quite reach our shoulders, if we were standing, would toss over to me, at random, without announcing that he was doing so, or giving me any warning, a tennis ball he’d found one morning, in the lot of the business park out front of our building, and that would bounce, each occasion that he lofted it, off the carpet behind my chair, or off my computer, or sometimes off my head, in which case I’d pretend to be annoyed, and would threaten to keep the ball on my side, and to not return it to him, though in fact I was amused, and was happy he was there, for he kept the day from becoming tedious, though I never told him this.