Everyone knows how a queue works. It's a line of people where the person at the front gets served first. But Danish researchers have recently made a shocking suggestion - that queuing on the basis of last-come-first-served may sometimes be more efficient.
The principle of first-come-first-served is simple, and it's fair. Who could possibly argue with it?
Well, one person is Prof Lars Peter Osterdal of the University of Southern Denmark.
"Queues, it's a wonderful example of a waste of time," he says.
"The problem with a regular queue where you serve first those who arrive first is that people tend to arrive too early."
Osterdal and his colleague, assistant professor Trine Tornoe Platz, studied situations where a service opens at a particular time and closes after every person has been served. Airlines that do not assign seats before boarding provide a good example.
Under the first-come-first-served system passengers arrive early and wait in line to get on to the plane because those who are first in line get the seat they want.
But the researchers experimented with different queuing systems, and when they told volunteer queuers that people would be selected from the queue and served at random, the average wait was reduced.
The best system, however, turned out to be last-in-first-out - or to put it another way, last-come-first-served - with the person who arrives last getting served first.