Dario Alequin/INFphoto.com
John Mayer has a one last parting gift for former girlfriend Jennifer Aniston–a tell-all exposé!

The “Clarity” rocker, who ended his twelve month romance with the screen sweetheart for the second time last week, has been overheard telling pals that he is considering penning an unflattering book about Aniston and his ill-fated relationship with her.

“John just can’t keep his mouth shut,” a Mayer pal tells Star, “and he’s telling friends that he’s thinking of going public with all their juicy secrets.”

So how much embarrassing info could John reveal? Apparently plenty.

Star writes: For one, Jen made a slip of the tongue calling John “Brad”… while they were in bed! He also knows all about her obsessive exercise regime, embarrassing TV viewing habits, devotion to astrology and numerology and has witnessed the actress throw fits!