Prepare red ice cubes in advance if using (mix water with red food coloring and freeze).
Fill a highball glass with regular ice cubes.
In a cocktail shaker, combine vodka, rum, tequila, gin, triple sec, blue curaçao, lemon juice, and simple syrup.
Add ice to the shaker and shake vigorously for 15-20 seconds until well-chilled.
Strain the mixture into the prepared glass.
Slowly pour cola over the back of a bar spoon to create a layered effect.
Gently add a splash of grenadine (or use red ice cubes).
Garnish with a lemon wheel.
The key to beautiful layers is pouring each ingredient slowly. The heaviest ingredients will sink to the bottom, creating the red, white, and blue effect.