Jennifer Aniston is getting singing lessons from ex-boyfriend John Mayer. The Hollywood star is preparing for a role in new movie The Goree Girls, about a group of women prisoners who start a country music band while locked up. She was worried about her singing voice and decided to ask Mayer for tips on how to give a polished performance. “Mayer’s been giving her private singing and guitar lessons to prep for the role,” a source said. Jennifer and John’s on/off relationship ended last year, with her apparently annoyed with the amount of intimate details about their romance he divulged to the public. The 41-year-old actress is now dating her The Bounty Hunter co-star Gerard Butler.