Drain the pineapple juice into a small bowl and add the teriyaki sauce. Measure three tablespoons of the marinade and place it in a shallow dish. Add the pineapple slices to the remaining marinade, and turn to coat them on all sides.
Shape the ground beef into four patties. Lay the burger patties in an 8-inch square baking dish, then pour the remaining teriyaki marinade over the patties. Soak in the marinade for 5 to 10 minutes, turning them once.
Remove the burgers from the marinade and discard the marinade. Cover and grill the burgers over medium heat or broil them four inches from the heat source for six to nine minutes on each side. The burgers are done once a digital thermometer reads 160°F.
While the burgers are grilling, saute the onion in butter in a small skillet for about five minutes or until tender. Set aside.
Remove the pineapple slices from the marinade and discard the marinade. Lay the pineapple slices on the hot grill or under the broiler; cook them until they’re heated through.
Put a lettuce leaf and some sauteed onions on the bottom burger buns. Add a burger patty next, followed by a slice of cheese and a slice of grilled pineapple. Finally, add a strip of bacon and the top bun.