Garnish this twist on a classic tequila cocktail with some fringe: Peel a wide strip of grapefruit peel with a vegetable peeler, then snip along its length. Groovy!
Combine all ingredients, except garnish, in a quart-size zip-top bag. Seal bag and freeze overnight. To serve, massage the bag to break up mixture. Tip slushie into a glass. Add garnish and serve immediately.
Make a bigger batch in a gallon-size zip-top bag for serving at a party.