Crockpot Pork Barbecue

4 lb. boneless pork butt or shoulder
1 can/bottle of beer
1 bottle barbecue sauce (the hickory is the best)
1 large onion, thinly sliced
4 tablespoons brown sugar

Trim all possible fat from roast. Place in crockpot, mix beer, bbq sauce and sugar and pour over roast. Add onions. Cover and cook on LOW for 8 to 10 hours or until pork can be easily shredded. Remove pork from crockpot, and shred in a bowl. Return pork to crockpot and let cook in the sauce another 20 minutes or so. Serve as sandwiches in buns.