Old Man Goes into a Pub...

Heard a good joke tonight when we had some friends round for dinner. An old man goes into a pub and orders three pints of bitter. He then goes off to a table and proceeds to take a sip from each beer in turn. When he finally returns the empty glasses the barman says, "I hope you don't mind me asking, but why did you take three pints of beer just now?". The man says, "Well, I've got a brother in the US and a brother in Australia, and once a month we agreed to have a drink together". "That's nice", says the barman. A month later the same guy comes back, but this time he only orders two drinks. When he returns the empty glasses the barman says, "I hope you don't mind me asking, but has something terrible happened?". The old man replies, "Oh no, my doctor said I should stop drinking is all".