1/2 a fluid ounce or 1.5 centilitres of Irish Cream
1/2 a fluid ounce or 1.5 centilitres of Dark Rum
1/2 a fluid ounce or 1.5 centilitres of Peppermint Schnapps

Mix in a double shot glass. I usually use a little less rum and a little more Irish cream, and only high quality stuff, or it tastes funny. This drink tastes like a chocolate mint, and it catches up with you fast!