Fill tumbler with ice. Lean to 45 degree angle and pour crème de menthe down the side of the glass to fill bottom. Repeat pour with Rumplemintz and Vodka. Do not stir. The intent is to make layers with the liquors (so that it looks like an iceberg.) Stick a straw in the middle of the drink and drink the whole drink at once through the straw.
Serve in a Old Fashioned Glass