1/3 a fluid ounce or 1 centilitre of Bailey's Irish Cream
1/3 a fluid ounce or 1 centilitre of Kahlua
Splash of Peppermint Schnapps

Pour the Bailey's first. Then tilt the glass and pour the Kahlua in so it slides under the Baileys and forms a distinct separate layer. Finally pour the Peppermint Schnapps in last and let settle out on top. If done correctly there will be three distinct color layers and the concoction will taste like a peppermint patty.