Fill a high ball glass with ice, then pour cola over ice.
Add the Grenadine syrup to the cola and stir together.
Garnish with a maraschino cherry and enjoy!
Notes
Use cold ingredients: Starting with chilled cola helps keep the drink fizzy longer.Don't over-stir: A gentle stir mixes everything together without removing the carbonation.Serve immediately: Roy Rogers drinks taste best while they're cold and bubbly.Use clear glasses: The rich color looks especially pretty in a tall glass.