I'm always on the lookout for eye-catching reflections. Someone was working on his car the other day, the dark hood propped straight up. I asked the driver if it was OK if I took a few shots. He was a bit puzzled by my request, but said it was alright. I didn't want to start shooting and have the driver wonder what kind of loon was imaging his car's hood.
Even when the hood was closed, it still created interesting effects, the lined surface creating double images depending upon the angle.