The Funniest Irish Joke of All Time

(Various versions of this circulate: this one is the shortest, though others, with more detail, can be even funnier if told by the right sort of narrator)

An Irish man walks into a pub. The bartender asks him, "what'll you have?"
The man says, "Give me three pints of Guinness please."
So the bartender brings him three pints and the man proceeds to alternately sip one, then the other, then the third until they're gone. He then orders three more.
The bartender says, "Sir, I know you like them cold. You don't have to order three at a time. I can keep an eye on it and when you get low I'll bring you a fresh cold one."
The man says, "You don't understand. I have two brothers, one in Australia and one in the States. We made a vow to each other that every Saturday night we'd still drink together. So right now, my brothers have three Guinness Stouts too, and we're drinking together.
The bartender thought that was a wonderful tradition.
Every week the man came in and ordered three beers. Then one week he came in and ordered only two. He drank them and then ordered two more.
The bartender said to him, "I know what your tradition is, and I'd just like to say that I'm sorry that one of your brothers died."
The man said, "Oh, me brothers are fine----I just quit drinking."