Begin by prepping the watermelon, lemons, and mint by removing watermelon rind and seeds, quartering the lemons and removing seeds, and removing mint stems.
Place the watermelon, lemons, half the mint, sugar, 2 cups of water, and a few ice cubes in a blender.
Blend until the lemons and watermelon are crushed. The mixture will be slightly foamy at this point.
Strain the mixture and add in remaining water and vodka.
Muddle (or juice) the halved lemon and distribute evenly into all the glasses.
Serve with ice and garnish with mint leaves, watermelon slices, and lemon slices. Enjoy!
Notes
For a fun twist, freeze mint into your ice ahead of time to add more color to the glasses when you serve them. Enjoy!