A riot policeman uses a baton to hit a rioting University of Nairobi student in Kenya's capital Nairobi, in this May 20, 2014 file photo. (Photo by Noor Khamis/Reuters)

A young Thai man jumps in the air and cheers as his rocket takes off at the Bun Bang Fai Rocket Festival on May 10, 2015 in Yasothon, Thailand. (Photo by Taylor Weidman/Getty Images)

Model Christine Teigen attends the 2014 Billboard Music Awards at the MGM Grand Garden Arena on May 18, 2014 in Las Vegas, Nevada. (Photo by Kevin Mazur/Billboard Awards 2014/WireImage)

Iggy Azalea (L) and Ariana Grande perform onstage during the 2014 Billboard Music Awards held at MGM Grand Garden Arena on May 18, 2014 in Las Vegas, Nevada. (Photo by Michael Tran/FilmMagic)

Singer Katy Perry arrives at the Metropolitan Museum of Art Costume Institute Gala 2015 celebrating the opening of “China: Through the Looking Glass” in Manhattan, New York May 4, 2015. (Photo by Lucas Jackson/Reuters)

Birds made of recycled tires are displayed in a shop located on the Panamerican highway near Catarina town, May 7, 2015. Salazar recycles used tyres to make bird figurines and sofas to sell in his shop located on the Panamerican highway. (Photo by Oswaldo Rivas/Reuters)

Farmers harvest cocoa fruits at a plantation in Gantarang Keke Village, South Sulawesi, Indonesia May 8, 2015. Sulawesi is at the heart of Asia's largest cocoa producing region, and is where some international confectioners are looking to boost output to feed growing demand for chocolate in the region. (Photo by Yusuf Ahmad/Reuters)

North Koreans wave flower bouquets and balloons as they march during a parade at the Kim Il Sung Square on Tuesday, May 10, 2016, in Pyongyang, North Korea. (Photo by Wong Maye-E/AP Photo)