An Irishman walked into a bar in Dublin, ordered three pints of Guiness
and sat in the back o fthe room, drinking a sip out of each one in turn.
When he finished them, he came back to the bar and ordered three more.
The bartender asked him, "You know, a pint goes flat after I draw it; it
would taste better if you bought one at a time." The Irishman replied,
"Well, you see, I have two brothers. One is in America, the other in
Australia, and I'm here in Dublin. When we all left home, we promised
that we'd drink this way to remember the days when we drank together."
The bartender agreed that it was a nice custom and left it at that.

The Irishman became a regular in the bar, and always drank the same way:
He ordered three pints and drank them in turn.

One day, the Irishman came in and ordered two pints. All the other
regulars noticed and fell silent. When he came back to the bar for the
second round, the bartender said, "I don't want to intrude on your grief,
but I wanted to offer my codolences on your great loss." The Irishman
looked confused for a moment, then a light dawned in his eye. He laughed.
"Oh no," he said, "everyone's fine. I've just quit drinking.