When you need to shit in the Illinois river and the Asian carp start eating your beef stew. You feel sensual and sexy. You start jacking off. The Asians love it even more. The Asian carp start feeding off of your jizz. You enjoy it and feel a calm sense of peace that you haven’t felt since you saw your mom fuck your sister in the living room at noon when you came back from lunch at your factory job and jerked off in the corner on that old beige towel. You didn’t wash the towel and placed it back on the towel rack.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.