Young people fight for fun with their pillows, during the International Pillow Fight Day at the Place des Grottes, in Geneva, Switzerland, Saturday, April 4, 2015. The annual International Pillow Fight Day takes place in hundreds of cities around the world. (Photo by Salvatore Di Nolfi/AP Photo/Keystone)

A young woman dressed as a zombie takes part in a zombie parade as part of the Brussels International Fantastic Film Festival 2014 in Brussels, Belgium, 12 April 2014. More than a hundred of participants took to the streets of Brussels. (Photo by Ulien Warnand/EPA)

An adult chimp plays with a young chimp at Chimp Haven in Keithville, La., Monday, February 18, 2013. One hundred and eleven chimpanzees will be coming from a south Louisiana laboratory to Chimp Haven, the national sanctuary for chimpanzees retired from federal research. (AP Photo/Gerald Herbert)

An climber ascends a silo covered in ice in Cedar Falls, Iowa, United States, January 17, 2016. The owners have connected hoses to the top of the silo and spray it with water in winter months to freeze the exterior for climbing. (Photo by Jim Young/Reuters)

A student gets off a police vehicle which carried her to a high school to arrive in time for a college entrance exam in Seoul, South Korea, Thursday, November 18, 2021. About 510,000 high school seniors and graduates across the country are expected to take the College Scholastic Ability Test. (Photo by Ahn Young-joon/AP Photo)