A customer buys a box of bullits and a target of Osama Bin Laden October 3, 2001 at Blue Ridge Arsenal in Chantilly, VA. Guns sales have risen across America since the September 11th terrorist attacks. (Photo by Mark Wilson/Getty Images)

A man speaks on his mobile phone on May 31, 2011 in New York City. In a new report by 31 scientists meeting at the World Health Organization's International Agency for Research on Cancer (WHO/IARC) it was found that using a mobile phone may increase your risk for certain kinds of brain cancers. While further scientific work will be conducted, the group of scientists from 14 countries classified cell phones in the carcinogenic category 2B, which is similar to the pesticide DDT and gasoline engine exhaust. (Photo by Spencer Platt/Getty Images)

A billboard for JELL-O stands at the corner of Grand Street and West Broadway on August 2, 2011 in New York City. The billboard acts as a mood-meter by analyzing Twitter and guaging the number of happy and sad emoticons used at any given moment, causing the billboard's face to change between a smile and a frown. (Photo by Andrew Burton/Getty Images)

International artist Yvette Mattern shows her stunning laser rainbow projection, Global Rainbow, on March 1, 2012 in Whitley Bay, England. The light installation celebrates the London 2012 Cultural Olympiad in the north-east of England. The Global Rainbow has previously lit up the skies of Germany, France and the United States. The projection will shine along the North Tyneside coastline for 4 days, before moving to other locations in the UK. (Photo by Bethany Clarke/Getty Images)

Actress Bella Thorne attends the Teen Choice Awards 2015 at the USC Galen Center on August 16, 2015 in Los Angeles, California. (Photo by Steve Granitz/WireImage)

A visitor kneels down nex to an iCub robot made by the Italian Institute of Technology at the scientists congress IROS 2015 in Hamburg, Germany October 2, 2015. The robot congress is organized by TAMS group (Technical Aspects of Multimodal Systems) of Hamburg's university. (Photo by Fabian Bimmer/Reuters)

The CBRE Urban Photographer of the Year competition – now in its ninth year – encourages professional and amateur photographers to capture cities at work. Here: Dog Walker – 15:00. The competition allows photographers to enter up to 24 images, one representing each hour of the day. (Photo by Johanna Siegmann)

A surfer runs down the beach past hundreds of Barbie dolls comprising the sculpture 'Wave 2' by West Australian artist Annette Thas on Tamarama Beach during the 19th annual Sculptures by the Sea exhibition in Sydney, October 23, 2015. Sydney's coastal walk between Bondi and Tamarama has been transformed into a temporary sculpture park featuring over 100 sculptures from Australian and international artists, billed as the largest free sculpture exhibition in the world. (Photo by Jason Reed/Reuters)