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
1/2 pint or 23.5 centilitres of Guinness

Pour Bailey's, Kahlua and Jamesons' in order in a shot glass (Bailey's at the bottom). Drop or slide the shot into a half pint of Guinness Stout. The shot, if dropped in carefully, looks like a Guinness inside a Guinness. The Carbomb is to be consumed in one long swallow. Mind your teeth as the shot slides forward. The incredible taste is worth the risk.