Place the frozen precooked meatballs into a crockpot or a large saucepan. Pour the chili sauce and grape jelly over the meatballs. Stir to ensure the meatballs are coated evenly with the sauces.

If using a crockpot, cover and cook the meatballs on HIGH for 2 to 3 hours or on LOW for 4 to 6 hours, until the sauce is hot and the meatballs are heated through. Alternatively, if using a saucepan on the stove, cover and simmer the meatballs over medium heat for about 10 minutes, stirring occasionally, until the sauce is bubbling and the meatballs are hot. I like to stir the meatballs once or twice during cooking to make sure they're evenly coated with the sweet and tangy sauce.

Once the meatballs are fully heated and the sauce is hot, serve them directly from the crockpot or saucepan using a serving spoon or toothpicks. Alternatively, transfer the meatballs and sauce to a serving dish for presentation.