Pour the chilled sports drink into the blender.
Add the ice cubes to the blender with the sports drink.
Secure the lid on the blender and blend on high for about 30-45 seconds, until the mixture is thick and slushy with a smooth, icy texture.
Stop the blender and check the consistency; if it’s too thick, add a splash more sports drink and blend briefly again.
Pour the slushie into glasses, using a spoon if needed to serve any remaining ice in the blender.
Serve immediately with a straw or spoon for a cool, tangy treat.