Gunfire erupted at a Denver pot celebration Saturday, injuring two people and scattering a crowd of thousands who had gathered for the first 4/20 counterculture holiday since the state legalized marijuana... Photo: A woman smokes a large marijuana joint at the Vancouver Art Gallery during the annual 4/20 day, which promotes the use of marijuana, in Vancouver, British Columbia April 20, 2013. (Photo by Ben Nelms/Reuters)

Zookeepers measure the length of a pueblan milk snake in the Reptile House of ZSL London Zoo as part of their annual weighing and measuring of their animals on August 25, 2011 in London, England. The heights and weights of over 750 different animal species at the zoo are recorded into the International Species Information System, to monitor their health and share the data with other zoos across the world. (Photo by Oli Scarff/Getty Images)

A participant smiles at the annual Christopher Street Day parade on Kurfuerstendamm in Berlin, Germany, June 27, 2015. (Photo by Fabrizio Bensch/Reuters)

Women in traditional costumes wait for a statue of the El Carmen Virgin to be carried into the sea during a procession in Malaga July 16, 2015. Many seaside towns celebrate the annual feast of the El Carmen Virgin, who is worshipped as the patron saint of sailors. (Photo by Jon Nazca/Reuters)

Festival-goers enjoy the mud during the annual Boryeong Mud Festival at Daecheon Beach on July 18, 2015 in Boryeong, South Korea. The mud, which is believed to have benefical effects on the skin due to its mineral content, is sourced from mud flats near Boryeong and transported to the beach by truck. (Photo by Chung Sung-Jun/Getty Images)

A devotee of the Chinese Jui Tui Shrine has his face pierced with metal rods during a street procession during the annual Vegetarian Festival in the southern Thai town of Phuket on October 19, 2015. During the festival, which begins on the first evening of the ninth lunar month and lasts nine days, religious devotees slash themselves with swords, pierce their cheeks with sharp objects and commit other painful acts to purify themselves, taking on the sins of the community. (Photo by Nicolas Asfouri/AFP Photo)

Kacey Musgraves performs at the 49th annual CMA Awards at the Bridgestone Arena on Wednesday, November 4, 2015, in Nashville, Tenn. (Photo by Chris Pizzello/Invision/AP Photo)

Photographer Jamie McCarthy and Lori Levine attend Moto X presents Heidi Klum's 15th Annual Halloween Party sponsored by SVEDKA Vodka at TAO Downtown on October 31, 2014 in New York City. (Photo by Mike Coppola/Getty Images for Heidi Klum)