Step 1: Place ice cubes and salt in a quart-sized Ziploc bag.
Step 2: Place juice in a sandwich-sized Ziploc bag, press out all the air and seal tightly. If it isn't sealed tightly enough, salt will get in and it won't taste good.
Step 3: Place the small bag of juice IN the larger bag of ice and seal. The larger bag will be holding the ice, salt, and the baggie of juice. *PLEASE NOTE: You will have two separate bags – a quart bag with ice and salt, and a sandwich bag with juice.
Step 4: Shake for about 3-5 minutes or until juice gets slushy. If your hands get too cold, wrap a dish cloth around the bag or use gloves and continue shaking.
Step 5: If your slushy isn't getting slushified. Add more ice and salt to the outer bag and keep shaking.
Step 6: Pour slush into a cup and serve immediately.