As shown here, you will need to freeze ahead 1 cup of watermelon chunks.
In a food processor, add about 1 cup frozen watermelon, about 1/2 cup ice cubes, and about 1/2 cup lemonade. Add enough liquid until you get a pourable consistency.
This is a non-creamy version using all lemonade and no milk.
You'll need a spoon and straw to sip all of this sweet treat.
This is a creamy version using 1/4 cup skim milk and 1/4 cup lemonade. Chill out and Enjoy!