Clever=Engineer?

Three engineers and three accountants were traveling by train to a conference. At the station, the three accountants each bought tickets and watched as the three engineers bought only a single ticket. "How are three people going to travel on only one ticket?" asked an accountant. "Watch and you'll see," answered an engineer.

They all boarded the train. The accountants took their respective seats, but all three engineers cramed into a restroom and closed the door behind them. Shortly after the train departed, the conductor came around collecting tickets. He knocked on the restroom door and said, "Ticket, please." The door opened just a crack and a single arm emerged with a ticket in hand. The conductor took it and moved on.

The accountants saw this and agreed it was quite a clever idea. So after the conference, the accountants decided to copy the engineers on the return trip and save some money (being clever with money, and all that). When they got to the station, they bought a single ticket for the return trip. To their astonishment, the engineers didn't buy a ticket at all. "How are you going to travel without a ticket?" said one perplexed accountant. "Watch and you'll see," answered an engineer.