Was out in the back yard shooting after dark, with the porch flood light on my target bag. There I am, minding my own business and doing one of the safest things I can think of doing. Just shooting some arrows with a safe backstop, not a care in the world. Out of nowhere (well actually out of a big oak tree) came an acorn. I'm too darned tired to figure out how high it would have to fall from to reach terminal velocity, but this thing was coming RDF (real darned fast). Put a gash in my outstretched bow arm and cut a little artery so that I was doing a good imitation of a well hit deer. A few seconds later one hit the roof of the little tool shed I was standing near not more than a foot from my head. I heard a voice saying "Run, Forest, RUN!"