In a slow cooker, dump in the chicken and cover with barbecue sauce.
Cook on high for 3-4 hours or on low for 6-7 hours. When done, it should easily shred with a fork.
Right before serving, butter both the top & bottom of the buns. Place butter-side up on a cookie sheet and bake at 400 for about 5 minutes.
Place the shredded chicken on the buns. Enjoy!