A ukulele player joke

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