Penal exception clause – prohibits slavery, except as a punishment for a crime

This is the basis of the fictional sitcom ("Jerry") written by Jerry and George in Seinfeld.

I was pretty sure that some of the spam calls I received for awhile were from a prison - because they were absolutely unwilling to go off-script, no matter what I did on my end.

Even the ones that were obviously coming from overseas, I would occasionally get a pre-recorded voice saying "hold on a second", followed by a pause (during which the "caller" was presumably typing), and then a clear text-to-speech robotic voice telling me to fuck myself.