Place frozen meatballs in the slow cooker and top with drained pineapple (reserve the juice and set aside), green pepper and red pepper.
In a mixing bowl, whisk together pineapple juice, brown sugar, cornstarch, vinegar and soy sauce.
Pour sauce in slow cooker and mix everything to combine.
Cover and cook on low for 3-4 hours or until heated through.
Serve over cooked rice.
Notes
You do not need to thaw frozen meatballs before cooking. Simply place the frozen meatballs directly into the slow cooker, and let the slow cooker do the work for you!