Prospective flight attendants listen to their instructor during an etiquette training course at Indigo Airlines' Ifly training centre in Gurgaon on the outskirts of New Delhi November 18, 2014. (Photo by Adnan Abidi/Reuters)

Planes land in fog at Heathrow Airport, west London on January 4, 2014, as heavy fog covers a many parts of the south east. (Photo by Steve Parsons/PA Images via Getty Images)

Manuelle aka the Snake Woman poses for photographs with a beer as she promotes the fnnual Beer Festival Oktoberfest in Cologne, Germany on September 22, 2014. (Photo by Federico Gambarini/EPA/EFE/Rex Features/Shutterstock)

A North Korean soldier kicks a pole along the bank of Yalu River near the North Korean town of Sinuiju, opposite the Chinese border city of Dandong, February 4, 2014. (Photo by Jacky Chen/Reuters)

Gus Palmer (Kiowa, at left), side gunner, and Horace Poolaw (Kiowa), aerial photographer, in front of a B-17 Flying Fortress. MacDill Field, Tampa, Florida, ca. 1944. (Photo and caption by 2014 Estate of Horace Poolaw)

A woman uses a electronic vaporizers with cannabidiol (CBD)-rich hemp oil while attending the International Cannabis Association Convention in New York, October 12, 2014. (Photo by Eduardo Munoz/Reuters)

A man poses as “Lemongrab” from Adventure Time outside the MCM Comic Con at the Excel Centre in East London, October 25, 2014. (Photo by Andrew Winning/Reuters)

People dressed as a zombie taking part in Zombie Parade on a streets of Belgrade during a zombie walk in Belgrade, on October 26, 2014. The zombie walk is part of the events of upcoming Serbian film fiction festival. (Photo by Oksana Toskic/SIPA Press)