Washington, June 20 : Cameron Diaz has revealed that she ''wasn''t uncomfortable'' doing the sex scene with her ex-boyfriend Justin Timberlake in their movie ''Bad Teacher''.The former couple - who dated for almost four years until December 2006 - star together in the comedy movie in which the actress'' character Elizabeth Halsey romantically pursues Timberlake''s alter-ego Scott Delacorte, and