Juice your grapefruits, also make space in your freezer for a 9x13 baking sheet to lie flat.

Either using a small saucepan, or a microwaveable glass container, heat up 1 cup grapefruit juice and 3/4 cup sugar at 30 second intervals until the sugar has dissolved (stirring between intervals).

Once the sugar has dissolved, combine the sugar grapefruit syrup and the rest of the grapefruit juice.

Transfer to the 9x13 baking sheet, and freeze for 30 minute intervals, using a fork to scrape and break up the ice pieces until it resembles glittery, shaved ice. This may take 3-4 hours depending on the strength of your freezer.

Serve immediately, because if left in the freezer for long without some scraping/breaking up with a fork, the pieces will stick together and you'll kind of have frozen chunks of shaved ice. (Plus, my batch barely lasted that long anyway).