Shake the vodka and creme de cacao with ice, then pour into a martini glass. Add a small splash of creme de menthe (it should sink to the bottom of the drink and settle there). Finally, add the "after eight" stick and mint as a garnish.
Similar to a chocolate martini, but it becomes minty near the end and the chocolate/mint stick is a nice finish. After you serve the drink, they're welcome to stir the drink to give it a pale green/blue tinge and make every sip minty rather than just the last two.