The most constriction I got from my friendly little guy Crowley (ball python) was when I had him around my neck he squeezed a little tight so all I did was gently tug on the snake and he loosened up. He went from being a neck snake all the time to not caring about wrapping around the neck since then. I wonder if his little brain was thinking "I don't want to hurt mommy so I won't wrap around necks no more.", or more likely he just grew too long and big to be a neck snake. He still goes on my neck but doesn't wrap around anymore, usually if I put his tail around to wrap him more securely he just plops the tail back off.