Late one Friday night, a policeman spotted a man driving very erratically through the streets of Dublin. They pulled the man over and asked him if he had been drinking that evening.
"Aye, so I have. It's Friday, you know, so me and the lads stopped by the pub where I had six or seven pints. And then there was something called "Happy Hour" and they served these mar-gar-itos which are quite good. I had four or five of those. Then I had to drive me friend Mike home and of course I had to go in for a couple of Guiness - couldn't be rude, ye know. Then I stopped on the way home to get another bottle for later..." Then, the man fumbled around in his coat until he located his bottle of whiskey, which he held up for inspection.
The officer sighed, and said, "Sir, I'm afraid I'll need you to step out of the car and take a breathalyzer test."
Indignantly, the man said, "Why? Don't ye believe me?!"