Willow in her Pikachu costume. Shannon Moore hide caption

itoggle caption Shannon Moore

South Korean rapper Psy performs his massive K-pop hit "Gangnam Style" live on NBC's "Today" show. Jason DeCrow/Invision/AP hide caption

itoggle caption Jason DeCrow/Invision/AP

"Freeway" Rick Ross was one of L.A.'s biggest crack dealers. via freewayenterprise.com hide caption

itoggle caption via freewayenterprise.com

A page from Pacioli's math encyclopedia, Summa de Arithmetica, Geometria, Proportioni et Proportionalita. via Jane Gleeson-White hide caption

itoggle caption via Jane Gleeson-White

President Barack Obama and Republican presidential candidate Mitt Romney at the first 2012 presidential debate in Denver, CO. SAUL LOEB/AFP/Getty Images hide caption

itoggle caption SAUL LOEB/AFP/Getty Images

A man selling helium balloons at a local festival on Feb. 19, in Athens, Greece. Oli Scarff/Getty Images hide caption

itoggle caption Oli Scarff/Getty Images