Do yourself a favour, and keep a load of watermelon in the fridge at all times because this drink is a banger any day of the week. Celebrate the good times with this tasty twist on a childhood classic.
Add all ingredients to a blender and blend thoroughly. (Leave out Vodka if making for children). Pour watermelon mixture into a container or baking dish. Cover and freeze for 4-6 hours, or overnight (it may not solidify completely due to the alcohol content). Remove frozen watermelon mixture from the freezer and add to a blender with sparkling water. Blend thoroughly, adding ice if necessary to reach the desired consistency. Pour into glasses and serve immediately.