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 pint in turn.
When he has finished all three, he comes back to the bar and orders three more.
The bartender says to him, "You know, a pint goes flat after I draw it; it would taste better if you bought one at a time."
The Irishman replies, "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 we all drank together."
The bartender admits that this is a nice custom, and leaves it there.
The Irishman becomes a regular in the bar and always drinks the same way: he orders three pints and drinks them by taking sips from each of them in turn.
One day, he comes in and orders only two pints. All the other regulars in the bar notice and fall silent. When he comes back to the bar for the second round, the bartender says, "I don't want to intrude on your grief, but I wanted to offer my condolences on your great loss."
The Irishman looks confused for a moment, then a light dawns in his eye and he laughs.
"Oh no," he says. "Everyone is fine. It's me - I've given up alcohol for Lent."