I was doing that this morning when the subway stopped in one of those areas where the ground is slanted. The subway was a little full and I started looking around. Then I started looking at the lunches I was holding and everyone with food imagining us having to ration it between the people in the subway car. Of course then eventually there’d have to be the scene with the person who was hiding food for themselves and whatnot. The air conditioning turned off briefly so I imagined that as another plot element that would aggravate the people in the car until they started arguing with each other.