8 cups cubed and seeded watermelon
1 cup strawberries, halved
1/2 cup fresh lemon juice
1 cup white sugar
2 cups water
(you may substitute Sprite or 7-up instead of water)
Combine all the ingredients and blend until it is smooth (you may have to do it in 2 batches!) A fun trick I have learned, is to cube the watermelon and freeze it ahead of time. Then you have a tiny bit of a slushy feel.
I found the recipe for this lemonade here.