1/2 a fluid ounce or 1.5 centilitres of Kahlua
1/2 a fluid ounce or 1.5 centilitres of Vodka
1/2 a fluid ounce or 1.5 centilitres of 7-Up

Layer in a lowball glass over ice. Then place a straw in the glass all the way to the bottom and drink as fast as you can.