I've thought that, too. Maybe you were the one to get me thinking about it - - have you mentioned it here before? Wherever it all comes from, plums, prunes, prune juice - - they're all good to me. :)
You put prunes in a container and top it with hot water for about 24 hours to stew them then you get your prune juice. Refrigerated makes an excellent cold drink or you can make prune wine.