An Irishman walks into a bar in Dublin, orders three pints of Guinness, and sits in the back of the room, drinking a sip out of each one in turn. Once finished with all three, he returns to the bar and orders three more.
The bartender says, "You know, a pint goes a bit flat a little time after I draw it. It might taste better if you bought one at a time."
His customer replies, "Well, you see, friend, I have two brothers. One is in America, the other in Australia, with myself still here at home. And when they left, we promised we'd always drink in threes this way, to remember the days when we all drank together."
The bartender allows this a darling custom, and leaves it at that.
The man becomes a regular in the bar, always drinking in his three-at-once fashion. Until one day . . . he comes in and orders just two pints.
The whole bar notices, and at once becomes deathly silent.
Naturally, it falls to the publican to broach the topic. When the customer steps up again and again orders just two more, the bartender says, "Far be it for anyone here to intrude on your grief. I speak for all in simply offering my condolences on your great loss."
The customer looks confused for just a moment, then the light comes back in his eyes and he laughs.
"Oh, no, no," he says, "everyone's fine. It's just that I've quit drinking."