Jessie J belts out the chorus to 'It's My Party' This image appears in the gallery:Summertime Ball 2014: The MUST-SEE Pictures From Our BIGGEST Ball Ever 65. Jessie J belts out the chorus to 'It's My Party' Picture: Derek Bremner 148 images See the full gallery: Summertime Ball 2014: The MUST-SEE Pictures From Our BIGGEST Ball Ever