Gun enthusiasts look over Smith & Wesson pistols at the NRA Annual Meetings & Exhibits on May 21, 2016 in Louisville, Kentucky. About 80,000 visitors are expected to attend the three-day event. (Photo by Scott Olson/Getty Images)

Runners gather at the start line for the annual “Santa Speedo Run”, a charity race through the streets of the Back Bay neighborhood of Boston. (Photo by Gretchen Ertl/Reuters)

Men dressed as soldiers pose with models before the opening of the Gamescom 2013 fair in Cologne,Germany, on August 23, 2013. The Gamescom convention is Europe's largest video games trade fair. (Photo by Ina Fassbender/Reuters)

A British fan waits to enter the Malmo arena ahead of the finals of the 2013 Eurovision Song Contest on May 18, 2013. (Photo by John MacDougall/AFP Photo)

An unknown number of guns are being built with the mechanisms, causing problems for the police and ATF officials. Photo: An ATF agent holds a generic unfinished receiver, back, and one that has been manufactured, front, at an ATF field office in Washington, on May 06, 2014. The ATF is trying to crack down on the trade in the makeshift guns by targeting shops and individuals who offer to turn the unfinished receivers into functional pieces for firearms. (Photo by Bill O'Leary/The Washington Post)

Burning Man 2013. The federal government issued a permit for 68,000 people from all over the world to gather at the sold out festival, which is celebrating its 27th year, to spend a week in the remote desert cut off from much of the outside world to experience art, music and the unique community that develops. (Photo by Neil Girling)

A model poses with “The Wellbeing Toilet” the winning entry from a Dyno-Rod Initiative to create a new design for the domestic toilet at Central Saint Martins on November 18, 2013 in London, England. The concept was commissioned to mark 50 years of Dyno-Rod and World Toilet Day on November 19th, 2013 The “Wellbeing Toilet” looks at the health and wellbeing aspect of getting rid of your bodily waste by being sculpted to enhance the position of your body by enabling you to squat rather than sit. (Photo by Miles Willis/Getty Images for Dyno-Rod)

A woman participates in the “Carnaval na Central” block party in Rio. (Photo by Felipe Dana/Associated Press)