Tickets Please

Two groups of three men are travelling by train to a conference. At the station, the first three men each buy tickets and watch as the second three buy only a single ticket.

"How are three people going to travel on only one ticket?" asks the first three.

"Watch and you'll see," answers the second three.

They all board the train. The first three take their respective seats, but the second three cram into a toilet and close the door behind them. Shortly after the train departed, the conductor comes around collecting tickets. He knocks on the toilet 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 first three men saw this and agreed it was quite a clever idea. So after the conference, they decide to copy them 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 second three do not buy a ticket at all.
"How are you going to travel without a ticket?", they say.

"Watch and you will see", is the answer.

When they board the train, the first men cram into a toilet and the others into another one nearby. The train departs. Shortly afterward, one of the second three leaves his toilet and walks over to the other toilet. He knocks on the door and says, "Ticket please."