Ziploc Bag Ice Cream

1/2 c half and half
1/2 t vanilla extract
1 ½ T sugar
6 T rock salt
Ice

Put half and half, vanilla and sugar into a pint or quart sized freezer bag. Be sure bag is completely sealed. Put enough ice into a gallon size freezer bag until about half full, add salt. Place the small bag containing half and half, vanilla and sugar into the large bag. Seal well. Shake and mix until the cream thickens (about 5 - 8 minutes) Remove small bag from large bag and enjoy.