1.In A Large Bowl, Mix Together Barbecue Sauce, Pineapple With Juice, Green Bell Pepper, Onion, And Garlic. 2.Arrange 4 Of The Chicken Breasts In The Bottom Of A Slow Cooker. Pour Half Of The Barbecue Sauce Over The Chicken. Place Remaining Chicken In Slow Cooker, And Pour Remaining Sauce Over The Top. 3.Cover, And Cook On Low For 8 To 9 Hours.