Two sisters
 

A cowgirl, who moved to Texas from Arkansas, walks into a The Buckhorn Saloon and orders three mugs of beer. She sits in the back of the room, drinking a sip out of each one in turn. When she finishes them, she comes back to the bar and orders three more.

The bartender approaches and tells the cowgirl, "You know, a mug goes flat after I draw it. It would taste better if you bought one at a time."

The cowgirl replies, "Well, you see, I have two sisters. One is in Australia, the other is in Dublin. When we all left our home in Arkansas, we promised that we'd drink this way to remember the days when we drank together. So I'm drinking one beer for each of my sisters and one for myself."

The bartender admits that this is a nice custom, and leaves it there. The cowgirl becomes a regular in the bar, and always drinks the same way. She orders three mugs and drinks them in turn. One day, she comes in and only orders two mugs. All the regulars take notice and fall silent.

When she 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 loss."

The cowgirl looks quite puzzled for a moment, then a light dawns in her eyes and she laughs. "Oh, no, everybody's just fine," she explains, "It's just that my husband and I joined the Church and I had to quit drinking."

Re: Two sisters
 

Good planning on her part to set up the tradition beforehand. Good one, thanks Oscar.