I wonder all the time why one of the Alice in Chains songs is named "Them Bones"? Shouldn't it be "their"? The whole verse goes like this "I believe them bones are me," and in my opinion it should use the possessive pronoun "their."
The same with name of the band "All Them Witches". I would say "All Their Witches"—then it would make sense to me, but clearly there's something I just don't know and don't understand.