1In a heavy skillet, cook the bacon until crisp. Remove it from the pan, crumble and set aside. Sauté the onion in the bacon drippings (or dump them and replace with a drizzle of oil) for about 5 minutes, until tender and beginning to turn golden.
2Transfer the onions to the bowl of a slow cooker and add the beans, ketchup, barbecue sauce, Guinness, brown sugar, mustard, vinegar, molasses, and a hit of salt and pepper. Cook on low for 6-8 hours.
3Stir the bacon back into the beans right before you serve them.