Three lawyers and three engineers are traveling by train to a conference. At the station, the three lawyers 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?" wonders one of the lawyers. "Watch, and you’ll see," replies one of the engineers.
They all board the train. The lawyers take their respective seats while all three engineers cram into a restroom and close the door behind them. Shortly after the train departs, the conductor comes around collecting tickets. He knocks on the restroom door and says, "Ticket, 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 lawyers see this and agree it is quite a clever idea. After the conference, the lawyers 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?" asks one perplexed lawyer. "Watch, and you’ll see," replies one of the engineers.