Add the green bell pepper and onion to the bacon drippings and cook for 5 minutes or until the vegetables soften, stirring often. Add the pork & beans, barbeque sauce, brown sugar and mustard and stir to combine. Bring to a boil then reduce to simmer, cover with a lid and cook for 1 hour. Stir occasionally so the beans don't stick to the bottom of the pan. Serve warm or at room temperature.