Mix 3 (28 ounce) cans pork and beans, ½ cup diced onion, ¾ cup barbecue sauce, ½ cup brown sugar and 2 Tablespoons yellow mustard in a 4-6 quart slow cooker.
Give the mixture a good stir.
Cover and cook on low for 3-5 hours.
Stir the beans gently a couple of times during cooking.
Right before serving, stir in ½ pound bacon, cooked and crumbled.
