@shel I usually bring up the concept of "private, like a private beach" and point to all the ways in which people have carved up the commons in blatantly dangerous ways. That seems to stop the confusion pretty quickly.
I honestly don't know what other term you'd use for "the stuff that people claim to own that they really can't and shouldn't be allowed to claim." I just say "people have coopted the concept of 'private property'" and run from there.
