Few things are as refreshing as watermelon. Add a little rum to the mix, as food and drink blogger Valerie Rice suggests, and you've got the perfect summer beverage. Combine 4 cups of diced watermelon with 1/8 cup sugar and the juice of 1 lime. Mash until all the watermelon is flattened and the juice is extracted. Add 4 cups of water and then strain into another pitcher. Add 2 ounces rum, pour over ice and garnish with lime.