Three Apple engineers and three Microsoft employees are traveling by train to a conference. At the station, the three Microsoft employees each buy tickets and watch as the three Apple engineers buy only a single ticket.

"How are three people going to travel on only one ticket?' asks a Microsoft employee. "Watch and you'll see," answers the Apple engineer.

They all board the train. The Microsoft employees take their respective seats but all three Apple engineers cram into a restroom and close the door behind them.

Shortly after the train has departed, 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 Microsoft employees saw this and agreed it was quite a clever idea.

 So after the conference, the Microsoft employees decide to copy the Apple engineers on the return trip and save some money (being clever with money, and all that). When they get to the station, they buy a single ticket for the return trip.

To their astonishment, the Apple engineers don't buy a ticket at all.

"How are you going to travel without a ticket says one perplexed Microsoft employee.

"Watch and you'll see," answers an Apple engineer.

When they board the train the three Microsoft employees cram into a restroom and the three Apple engineers cram into another one nearby. The train departs. Shortly afterward, one of the Apple engineers leaves his restroom and walks over to the restroom where the Microsoft employees are hiding.

He knocks on the door and says, "Ticket, please..."