On the Cover: John Mayer's $10M Tell-All

How's this for a parting shot: Big mouth John Mayer wants to spill the intimate details of his relationship with Jennifer Aniston in a no-holds-barred book — including the night Jen called him "Brad" in bed!

In the March 30 issue of Star — on sale now! — we report that as if getting dumped by the singer (twice!) isn't bad enough, he's talking about penning a book sharing the very intimate details of their relationship.

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

So just what embarrassing info could John reveal? Well the fella who held an impromptu press conference on a New York City street the first time they split has a lot to say, as we detail in in our magazine. 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!