Three years ago, Volkswagen launched its internationally acclaimed Piano Stairs as part of the so-called Fun Theory. To encourage people to take the stairs instead of the escalator, steps of the stairs in a Stockholm metro station were transformed into sound-producing piano keys. As a result, stair use increased with 66%. Here we’ve got another way to stimulate people to take the stairs instead of the escalator, although it doesn’t use the Fun Theory but rather a ‘Shame Theory’. New York-based street art blog Wooster Collective claims this intervention to be street art at its best. Simple, but utterly funny and a little provocative. The artist is unknown.