Cut bacon into 2-inch lengths. In a wide frying pan over medium heat, cook bacon until crisp; drain and set aside.
Combine beans, mustard, ginger, coffee, brown sugar, and bacon. Turn into a 3-quart casserole or 9x13-inch baking dish. (At this point you may cover and refrigerate until next day.)
Bake, covered, in a 350° F oven for 45 minutes.
Stir in rum. Cut pineapple slices in half and arrange over top. Return to oven, uncovered, for about 25 more minutes or until top is browned.
Servings: 10 to 12