It's the third week in January, three engineers and three accountants are travelling by train to a conference in Brighton. At the station, the three accountants each buy tickets and watch as the three engineers buy only a single ticket.
'How are three people going to travel on only one ticket?' asks an accountant. 'Watch and you'll see', answers an engineer.
They all board the train. The accountants take their respective seats but all three engineers cram into a toilet and close the door behind them. Shortly after the train has departed, the conductor comes around collecting tickets. He knocks on the toilet door and says, 'All tickets please.'
The door opens just a crack and a single arm emerges with a ticket in hand. The conductor takes it and moves on.
The accountants saw this and agreed it was quite a clever idea. So after the conference, the accountants decide to copy the engineers on the return trip and save some money. When they get to the station, they buy a single ticket for the return trip. To their astonishment, the engineers don't buy a ticket at all.
'How are you going to travel without a ticket?' says one perplexed accountant.' Watch and you'll see, 'answers an engineer.
When they board the train the three accountants cram into a toilet and the three engineers cram into another one nearby.
The train departs.
Shortly afterward, one of the engineers leaves his toilet and walks over to the toilet where the accountants are hiding. He knocks on the door and says, 'All tickets please.'