Ok, this one is from one of the girls I visit with from church, and her husband's family makes this every year. She let us try some when we visited her in the beginning of December, and you would never know it wasn't store bought. I didnt have the official recipe when I made it just before Christmas to take it to the family members, but I think I got it pretty close. Super easy and tastes like you got it from the store, but it makes twice as much for half the price.
1 gallon 2% milk
2 boxes of vanilla or eggnog flavored pudding (small boxes, and I used sugar free)
1 tbsp imitation rum flavoring
1 1/2 tsp nutmeg
Pour half the gallon of milk into a large bowl. With whisk or stick/immersion blender (you can use a regular blender, but you have to do it in smaller batches which would make it thicker and harder to pour), blend pudding into milk, then add rum flavoring and nutmeg. Pour back into the milk bottle, using funnel. Shake bottle well, and then chill overnight in refrigerator. Best if you make at least one day in advance, flavors meld better over time.