I saw this method on BH & G tv.

Take a pork sirloin (I use a large pork loin - not tenderloin)
cut it in half if necessary to fit in a crock pot. Cover outside of pork with salt, pepper and garlic. Add one or two sliced onions. Add a cup of root beer (yes root beer).

That's it. Cook on low for 8 hours (it's not as tender if you cook it on high). When ready to serve through it on the grill for a few minutes to get some burnt "outside". Now they made a barbeque sauce out of the "juice" in the crockpot but I just buy my favorite store bought (DO LOVE THE vinegar kind!)

Take two forks and shred the meat thinly. Serve with buns and barbeque sauce. It is very good and easy too!