Nothing's better on a hot day than homemade watermelon ice pops.
Working in batches, place watermelon and sugar (if using) in a blender. Puree until completely liquefied, stirring watermelon as necessary so all cubes are blended and mixture is smooth. Pour into twelve 3-ounce ice-pop molds or plastic cups. Insert sticks or wooden spoons into puree, and freeze until solid, at least 8 hours.