Three M.B.A's and three Software Engineers are traveling by train to a conference. At the station, the three Software Engineers each buy tickets and watch as the three M.B.A's buy only a single ticket. "How are three people going to travel on only one ticket?" asks an Software Engineer. "Watch and you'll see,"answers one M.B.A. They all board the train. The Software Engineers take their respective seats but all three M.B.A's 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 Software Engineers see this and agree that it was quite a clever idea. So after the conference, the Software Engineers decide to copy the M.B.A's 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 M.B.A's don't buy a ticket at all. "How are you going to travel without a ticket?" says one perplexed Engineer. "Watch and you'll see," answers one M.B.A. When they board the train the three Software Engineers cram into a restroom and the three M.B.A's cram into another one nearby. The train departs. Shortly afterward, one of the M.B.A's leaves his restroom and walks over to the restroom where the Software Engineers are hiding. He knocks on the door and says, "Ticket, please."