The "car bomb" refers to the fact that the drink is a "bomb shot" and also to the many car bombings that took place during the Troubles in Ireland. For this reason, the name is sometimes deemed offensive and some bartenders refuse to serve it. The drink is popular in the United States; however, it is virtually unknown in Ireland, and ordering it there is likely to cause confusion or offense.
To make the drink, whiskey is floated on top of Irish Cream in a shot glass, and the shot glass is then dropped into the stout. Once mixed, it must be drunk quickly because it will curdle. While Kahlúa was part of the original recipe, it is often excluded from the drink today. Some refer to that original recipe as a Belfast Car Bomb.