Add ice cubes to a highball glass and pour in the spiced rum. If using a flavored syrup, add with the ice.
Top off with cola, wait for the bubbles to settle and add more ice cubes if needed.
Squeeze a lime wedge over the top of the drink and then drop it into the cocktail. Use a drink stirrer/straw to gently combine the ingredients and serve immediately.
Notes
Feel free to substitute your favorite rum, light or dark.