A man walks into a bar and orders 3 beers and takes drinks in turns from each. After draining them he orders another, and goes about it the same way. After a while the bar tender comments on this, and points out it would be easier if he'd just drink 1 at a time. The man then explains that he's drinking like this in memory of his 2 brothers, who live in Australia and South America. He says that before they all went their separate ways, they used to all buy each other drinks. So now, they all buy 3 drinks at 7:00 PM, and drink each one as if they were another person. The bartender is quite touched, and gives him a free round. After finishing them off, the man pays the tab and leaves. He comes back the following night, and repeats the process. After a while the man becomes a regular, and 1 night, he walks in but only orders 2 drinks. The other men quiet, and a few bow their heads. The bartender comes over and says to the man: "allow me to offer my condolences." The man looks up and replies: "Oh, everything's fine. It's just that I recently joined the Mormon Church, and they said I'm not allowed to drink anymore."
(The original joke was of course worded much better, but its been a long time since I read it)