1 oz of Vodka
1 oz of Kahlua coffee liqueur
1-2 oz of Coca-Cola (or coke)
1 splash of half-and-half (or cream)
1 oz of dark creme de cacao (or chocolate liqueur)
Combine all ingredients in a cocktail shaker half-filled with ice cubes. Shake well and pour into an old-fashioned glass. Add Coca-Cola, and serve.