Commuters using the piano staircase in StockholmCome on, admit it... how many of you secretly wish you could recreate that famous scene from 'Big' with the giant piano keyboard?

Most of you, we're guessing. Well, now car company Volkswagen has used that secret desire to encourage people to get a little more exercise.

A team of workers have managed to transform a set of stairs at the Odenplan subway station in Stockholm, overnight, into a fully functioning piano keyboard.

And despite the escalator right alongside, commuters were soon found their curiosity (and sense of child-like wonder) getting the better of them, choosing to scale the steps whilst making their very own music.

In fact, 66 per cent more people than usual were soon climbing the stairs in preference to their standard glide up the escalator.

A video of the idea has since become something of an internet hit, with several people even posting their own musical attempts on YouTube.

A spokesman told the Daily Mail: "Fun can obviously change behaviour for the better. We call this the fun theory."

And Volkswagen will soon be launching a website entitled thefuntheory.com, which hopes to showcase various attempts to change behaviour for the better.

For the time being though, the following will have to suffice...