Place pork in a large crock pot (5 quart or bigger). Sprinkle liberally with salt and pepper. Pour the vinegar over it. Cook on LOW for 10 hours.
Let pork cool down and shred it, using two forks or your hands. Add barbecue sauce to shredded pork. (I discard all the liquid from the crock, but if you need you can add a little bit of it to the pork if it is too dry.) You can also keep part of the pork not shredded for other uses; it is delicious even without the barbecue sauce.