This guy goes into the bar Friday night and orders three beers, in fact every Friday night he goes into the bar and orders three beers and drinks them all by himself. Three beers...every Friday night. Not 2. Never 4. Always 3. Well, the bartender can't figure this out. Without fail this guy comes in.
The bartender finally says to the guy "Every Friday night you come in here and have three beers. There must be a story to this. You never order 2 beers, or 4 beers, always 3." The guy says "Yes there is a story." You see, me and my two buddies always went out for a beer on Friday night when we were in Vietnam. One night while we were drinking we decided that we could continue doing this when we return to the states. We also decided if one of us didn't make it the other two would drink the third ones beer. And if two didn't make it, the third guy would drink the other two beers. The other two didn't make it back so I'm drinking theirs." The bartender felt bad.
Well, the next Friday night the guy came back into the bar as usual but only ordered two beers. The bartender couldn't believe it. Friday after Friday this guy now orders only two drinks. This went on for some time and the bartender was so puzzled he just had to ask the guy about it.
The bartender says to him, "I noticed you have only been ordering two beers for the last few weeks. There has to be a story here."
The guy says, "Yes indeed there is a story. You see I joined the Mormon church and I can't drink beer any more."