An Australian tourist was sitting at the bar in an Irish pub when all of a sudden a guy yelled out "Number 47!", and all the other drinkers started laughing. A few minutes later another guy yelled out "Number 77!", and again everybody laughed.

The Australian thought this was a bit odd, so he asked the barman what was going on. The barman said "Well, its like this - these people have been drinking here for years, and they all tell the same jokes. So a couple of years ago we decided to give each joke a number, and now when someone starts telling a joke, if you think you know what it is you call out the number and if people think its a funny joke they will laugh."

The Aussie thought he'd give this a try. He waited until it was quiet and then stood up and shouted "Number 88!" and everybody laughed loudly and hysterically for ten minutes or more. People were falling over and crying with laughter. The pub was in uproar.

The Aussie said to the barman "So tell me, why did they laugh more at my joke than the others?"
And the barman said "Well, there are two reasons - firstly it was a very funny joke, and secondly, nobody had heard it before"