As you get prepared to enjoy many car bombs on Saint Patrick's Day, you may want to know a few things before you get too inebriated.
First, the Irish Car Bomb is an American cocktail -- it's only called Irish because of the use of Guinness, Baileys Irish Cream and Jameson Irish Whiskey.
Second, we call it a car bomb because when the shot of Baileys is dropped into the glass of Guinness, it bubbles up like an explosion. Because of the Irish ingredients, someone thought it was a good idea to name it an Irish Car Bomb. It was not. Car bombs are not taken lightly in Ireland and the name makes reference to a difficult time in Ireland -- one where many people were hurt, and times were hard. It's offensive and naming a drink after this time in history doesn't really make a lot of sense -- it's just insensitive.
Third, if you're going to make this drink, you need to know how to make it properly (and try to come up with a different name for it).
You won't find it in Ireland, it's mostly confined to the States and you can understand why some might find the name incredibly offensive.