Lady Gaga has admitted to past drug use in Vanity Fair and in other media -- revealing to Howard Stern how her father expressed his disappointment when he found out she was doing the hard stuff. However, a new book penned by a former friend is revealing rampant cocaine abuse when Gaga was a struggling musician on the Lower East Side.

In 'Rivington Was Ours: Lady Gaga, The Lower East Side and the Prime of Our Lives' Gaga's onetime pal Brendan Jay Sullivan spills the beans in tell-all fashion. The book is out Aug. 27.

In the tome, Sullivan recalls the time he watched Gaga rub white powder from her carpet onto her gums, saying, “It’s mint. I wish it was coke."

He also says Gaga told him she used to consume "bags and bags" of the white stuff. She revealed that she had one golden rule when snorting: That she did it solo while putting on her makeup. She said, "I’d get a delivery and then put on some Bowie and treat myself in the mirror. But I only ever did it alone. That was my one rule."

She didn't stick to that stipulation, according to her author and onetime "friend." They were hanging at Don Hill's, an NYC rock club, one night and she asked him to secure a supply of cocaine from a dealer known as "Devil."

"I just agreed to score drugs for us both and spend our entire night smoking way too many cigarettes and talking way too fast about ourselves," he writes. "Then I started to worry. She had a recording session in L.A. the next week. What if it ruined her voice?"

They blew off that supplier for one night.

Gaga also said that her NYU pals would help her score bags of coke. She told the author, "I'd be out with my friends and you’d catch one of them on the phone with their dads, pretending they needed the money to eat or to buy books or something, and they’d hang up and go to the ATM and take out more money to party."

In 2010, Gaga said any recent cocaine use is occasional as in a couple times a year, if that.

The book's contents regarding drug use aren't as shocking as they might seem. Gaga has admitted she used cocaine. However, this book might offer an insider's insight into her pre-fame (or pre-Fame) life, which is what monsters and critics will find interesting.

You'll notice a lot of Sullivan's details are similar to what she said about drugs on Stern's show two summers ago, so he may be cashing in with this book.