Make simple syrup by combining 1 cup water and 1 cup sugar in a small saucepan over medium heat. Warm until sugar has fully dissolved, then pour into a heat-safe container and let cool.
Peel and de-seed the cantaloupe, then use the largest hole on a box grater to shred the cantaloupe into a large bowl.
Fill a rocks glass halfway with crushed ice, fill the rest with the strips of cantaloupe, add milk or water to the 3⁄4 level of the glass, then a splash of the simple syrup, and give it a stir.