Pharrell Williams probably had no idea when he sang 'Happy' for the movie 'Despicable Me 2' just how big a hit it would become. From the videos colleges, towns and individuals are doing to the country superstars like Rascal Flatts performing it acapella on tour, and on last nights CMAFest 'Country's Night to Rock' on ABC. If you missed the show, watch Rascal Flatts and their band perform 'Happy'