Homemade Ice Cream in a Bag

Ingredients
2 tablespoons sugar
1 cup half and half
1/2 teaspoon vanilla extract
1/2 cup salt (The bigger the granules, the better. Kosher or rock salt works best, but table salt is fine.)
Ice cubes (enough to fill each gallon-size bag about half full)
1 pint-size ziplock bag
1 gallon-size ziplock bag

Instructions
Combine the sugar, half and half, and vanilla extract in the pint-size bag and seal it tightly.
Place the salt and ice in the gallon-size bag, then place the sealed smaller bag inside as well. Seal the larger bag. Now shake the bags until the mixture hardens (about 5 minutes). Feel the small bag to determine when it's done.