Fireworks explode over Elizabeth Tower housing the Big Ben clock in London. (Photo by Kirsty Wigglesworth/Associated Press)

A woman waters the plants outside her house in an alley at a slum in Mumbai October 28, 2014. (Photo by Danish Siddiqui/Reuters)

An installation with a copy of a tank is seen at a villager's house in the village of Vits, Belarus November 8, 2016. (Photo by Vasily Fedosenko/Reuters)

America’s Haunts, a trade association, estimates there are 1,200 for-profit haunted attractions in the U.S. plus another 3,000 haunted houses operated by charities that open for only a day or two every year. The commercial attractions collectively bring in from $300 million to $500 million annually. Fright Nights attendees make a turn through one of four haunted houses at this year's spooking season setup at the South Florida Fairgrounds. This house is named The Smiths and was created by Craig McInnis. (Photo by The Palm Beach Post)

A woman takes part in a four-minute flash mob pillow fight at the Old Town Square in Prague, Czech Republic, December 22, 2016. (Photo by David W. Cerny/Reuters)

Female of pygmy hippopotamus called Malaya from Netherlands in zoo in Dvur Kralove nad Labem, Czech Republic, February 22, 2016. (Photo by David Tanecek/CTK via ZUMA Press)

DJ David Guetta (R) and rapper Nicki Minaj perform onstage during the 2017 Billboard Music Awards at T-Mobile Arena on May 21, 2017 in Las Vegas, Nevada. (Photo by Mario Anzuoni/Reuters)