Jennifer Aniston's relationship with John Mayer is giving her a new sense of self,

"John is good in bed," a pal of the 30-year old singer-songwriter tells OK!. "Not just good, but sensational. Every girl I know who has slept with John says it was the best sex of their life. I'm not sure what exactly he does in bed, but after girls sleep with him, they're ruined. They get totally hung up on him and want more! Whatever John's secret is, he should market it. He could retire from the music industry."

"Jen's in a new relationship, and when you're having great sex, you dress to reflect how you feel. Instead of dark glasses and dull dresses, Jen's wearing short skirts and sexy tops. It's like sending a message to the world."

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