In a pitcher, combine pineapple juice, orange juice, tequila, and Sprite. Add a handful of ice and refrigerate for 1 hour to chill. You can skip this if everything is already cold.
Serve:
Measure ½ ounce of grenadine and add it to the bottom of a tall glass. Fill with crushed ice.
Pour the tequila punch cocktail into the glass and garnish with orange slices and maraschino cherries.
Notes
Turn this into a punch bowl, serves 12, by doubling up the amounts. To avoid measuring the grenadine as you fill the punch cups, add ⅓ cup of grenadine to the bowl and mix.