Cut 1 (4- to 5-lb.) bone-in Boston butt pork roast in half, and trim pork. Rinse and pat dry.
Sprinkle with 1/4 cup Smoky-Sweet BBQ Rub. Let stand at room temperature 30 minutes.
Place pork in a lightly greased 6-qt. slow cooker, fat sides up. Cover and cook on LOW 7 hours or until meat is tender and shreds easily.
Transfer pork to a cutting board, discarding liquid; cool slightly.
Shred pork with 2 forks. Stir 1 1/4 cups barbecue sauce into pork.
Return pork mixture to slow cooker; cover and cook on HIGH 30 minutes, or transfer pork mixture to a 2-qt. baking dish, and bake at 350° for 25 minutes.