In a large bowl, combine ground beef, breadcrumbs, egg, chopped onion, garlic, salt, and pepper.
Form the mixture into 1-inch meatballs and place them in the slow cooker.
In a separate bowl, whisk together the barbecue sauce, drained crushed pineapple, and soy sauce.
Pour the sauce mixture over the meatballs in the slow cooker, making sure they are well coated.
Cover and cook on low for 6-8 hours or on high for 3-4 hours.
Once cooked, gently stir the meatballs before serving. Garnish with fresh parsley if desired.