A sculpture entitled “Powerless Structures, Fig.101” designed by Danish artist Michael Elmgreen and Norwegian artist Ingar Dragset is unveiled on the Fourth Plinth in Trafalgar Square on February 23, 2012 in London, England. (Photo by Oli Scarff/Getty Images)

A tattoo artist applying ink on a girl's thigh at the 2016 Italian Tattoo Artists at the Palavela on September 17, 2016 in Turin, Italy. (Photo by Stefano Guidi/ZUMA Press/Splash News)

In this September 1, 2015 photo, street artists Jenaro de Rosenzweig, left, and Alejandro Revilla pose for a portrait behind a restaurant's window covered with a mural by artist Francisco Munoz, signed with his artist's name below, in the Roma Norte neighborhood of Mexico City. Rosenzweig and Revilla founded the “Street Art Chilango” cooperative in March 2013, which is filling neighborhoods with public art by local street artists. (Photo by Rebecca Blackwell/AP Photo)

A donkey savors warming temperatures after a long winter at the zoo in Warsaw, Poland, on Wednesday, April 8, 2015. (Photo by Czarek Sokolowski/AP Photo)

Look at the image for long enough and you can make the train change direction simply by thinking about it. Freaky.

Nepalese devotee women take a holy bath after offering prayers in Pashupathinath Temple premise during the month-long Swasthani Bratakatha festival, devoted to goddess Shree Swasthani in Kathmandu on February 8, 2016. Devotees recite Holy Scripture and women pray for wellbeing of their spouses throughout the month-long fast. (Photo by Skanda Gautam via ZUMA Wire)

A Kashmiri woman walks on a footbridge as it rains in Srinagar, June 24, 2015. This year's monsoon rains in India are officially forecast to be only 88 percent of the long-term average. (Photo by Danish Ismail/Reuters)

People slide down a 1,082 feet (330 metre) long inflatable water slide in Hong Kong, China August 22, 2015. (Photo by Tyrone Siu/Reuters)