Reminded me of my brother putting up chickens in the freezer. Picture this. He lived next door to a fast food joint with a lot of picnic tables for lunching in the outdoors.
Around lunch time he had over a dozen chickens and started chopping off heads and releasing them. The headless chickens raced around the yard, blood spurting, and tumbling randomly. White chickens were half red when they quit running. None got off the property but when he finished he noticed that the picnic tables were empty.
Actually two nails driven half way into the chopping block that are far enough apart for the neck and too small for the head to fit through works pretty well. You can stretch the neck out so you get the most meat and keep the fingers out of range. Chop on the nail side opposite of the head.
This reminded me of another incident. My mother complained to my dad that he was leaving too much neck with the head. The next batch came in with eyeballs but without the beak. There were no more complaints.