A competitor tries to swipe away some grease as he slips off the “gostra”, a pole covered in grease, during the celebrations for the religious feast of St Julian, patron of the town of St Julian's, outside Valletta August 30, 2015. In the traditional “gostra”, a game stretching back to the Middle Ages, young men, women and children have to make their way to the top of a pole and try to uproot one of the flags to win prizes. Photo by Darrin Zammit Lupi/Reuters)

An image of the popular video game “Angry Birds” is displayed on an iPod Touch on March 18, 2011 in San Anselmo, California. The “Angry Birds” mobile device video game developer Rovio is begnning the process of seeking an initial public offering (IPO). (Photo Illustration by Justin Sullivan/Getty Images)

Indigenous women from the Kamayura tribe take part in a demonstration of Huka Huka fight at the first World Games for Indigenous Peoples in Palmas, Brazil, October 29, 2015. (Photo by Ueslei Marcelino/Reuters)

Yippie leader Jerry Rubin, barred on December 4, from House Un-American Activities subcommittee hearing, aims a toy gun in “self defense” outside the Washington hearing room on December 5, 1969. Rubin showed up in his Santa Clause suit because he believed it was typical of the committee which, he said, “is a total circus”. (Photo by Bob Daugherty/AP Photo)

Leslie Cliff and his wife Violet, English figure skating pair. Olympic games of Garmisch-Partenkirchen (Germany), 1936. (Photo by Roger Viollet Collection/Getty Images)

Model Heidi Klum in front of Concorde jet after arriving for Victoria's Secret fashion show at Cannes Film Festival on May 16, 2000. (Photo by Marion Curtis/DMI/The LIFE Picture Collection/Getty Images)

Mae Zelinsky, left, and Betty O'Beda test ammunition on a .30 caliber rifle at a Remington Arms plant on April 30, 1943. Many women took over jobs that were left vacant when men went overseas to fight in World War II. (Photo by AP Photo)

Gunfire was brought to the steps of President Truman's Washington home, Blair House, as two assassins tried to kill the chief executive, November 1, 1950. One of the gunmen, Oscar Collazzo of New York, lay wounded at the bottom of Blair House's front steps after the president's police guard had finished their work, at the cost of one guards' life, Dec. 9, 1950. The second gunman was killed. (Photo by Harvey Georges/AP Photo)