Drain pineapple juice into a small bowl; add teriyaki sauce. Place 3 tablespoons in a resealable plastic bag. Add pineapple; toss to coat and set aside.

Shape beef into four patties; place in an 8-in. square baking dish. Pour the remaining teriyaki sauce mixture over patties; marinate for 5-10 minutes, turning once.

Drain and discard teriyaki marinade. Grill, covered, over medium heat or broil 4 in. from the heat for 6-9 minutes on each side or until a thermometer reads 160° and juices run clear. Meanwhile, in a small skillet, saute onion in butter until tender, about 5 minutes; set aside.

Drain and discard pineapple marinade. Place pineapple on grill or under broiler to heat through. Layer with lettuce and onion on bottom of buns. Top with burgers, cheese, pineapple and bacon. Open wide, and enjoy!