On a train there were a bunch of Liberal Arts Majors and a bunch of computer engineers who were headed to a big computer convention. Each of the Liberal Arts Majors had a train ticket. The group of engineers had only ONE ticket for all of them. The Liberal Arts Majors started laughing and making fun of them, figuring the engineers were going to get caught and thrown off the train.
When one of the engineers, the designated lookout, said "here comes the conductor", all of the engineers ran into the bathroom and locked the door. The Liberal Arts Majors were puzzled.
The conductor came aboard, said "tickets please", and got tickets from all of the Liberal Arts Majors. He then went to the bathroom and knocked on the door and said "ticket please". The engineers stuck the ticket under the door. The conductor picked it up and moved on. A few minutes later the engineers came out of the bathroom. The Liberal Arts Majors felt really stupid.
On the way back from the convention, the group of Liberal Arts Majors decided that they would try that method, too. They bought one ticket for the whole group. They met up with the engineers in the same car.
Again, the Liberal Arts Majors started snickering at the engineers. This time NONE of the engineers had tickets. When the lookout said "Conductor coming!", all the engineers went to one bathroom and all the Liberal Arts Majors went to the other bathroom.
Before the conductor came on board, one of the engineers left their bathroom, knocked on the Liberal Arts Majors bathroom, and said "Ticket please!"