Prisoners lose most of their rights. They have no privacy rights, they can be searched at any time without a warrant, they often don't get to vote, they don't get to own weapons, they don't have freedom of association, they don't get to choose their style of dress.
I've never seen the social contract, let alone signed it. I suppose I used to sort of believe that it existed, but that belief, like so many others I once held, has not survived the past decade or so. Certainly I believe in consequences, but they seem little better than random, though they quite rarely touch the wealthy/connected.