In a small saucepan, combine sugar and water over high heat. Once the water comes to a boil, reduce heat to low. Simmer, stirring often, until sugar is dissolved. Remove from heat and let cool.
Clean the outside of the cantaloupe and cut in half. Use a spoon to remove the seeds and a melon scraper to scoop out threads of the cantaloupe into a medium bowl. If a melon scraper is not available, slice the cantaloupe and grate the flesh into the bowl.
Place the grated cantaloupe flesh into the pitcher and add the cooled syrup. Fill with water. If using, add a splash of vanilla extract or some condensed/evaporated milk.
Serve chilled or with crushed ice.