Fill a tall glass with ice. Pour in the tequila and then the orange juice.
Pour in the grenadine and let it sink to the bottom of the drink.
Garnish with an orange slice and cherry. Serve immediately.
Notes
Make this cocktail for a crowd: add 2 cups of tequila and 4 cups of orange juice (for 8 servings) to a large pitcher and stir together. Chill for later. To serve, add some ice to a tall glass, pour in the OJ/tequila mixture, and then top with the grenadine before garnishing.