1/2 a fluid ounce or 1.5 centilitres of Bailey's Irish Cream
1/4 a fluid ounce or 7.5 milliliters of Kahlua
1/4 a fluid ounce or 7.5 milliliters of Jameson's Irish Whiskey

Pour into a shot glass in order (Bailey's at the bottom). The addition of the Jamesons' at the end causes the shot to boil/explode.