In the book, the Scream 3 star reveals she and 13 Playboy Playmates got high during a promotional trip to Hawaii and started making out with each other on a beach.
But she insists the experience was neither satisfying nor sexy - and she's convinced anyone reading her memoirs will feel repulsed by her recollection of the lesbian drug tryst.
She says, ""I had never done it before... and I wanted to have more than anybody else and we literally lost our minds.""
And she thought one of her Playmate pals was a tree!
McCarthy adds, ""I was like, 'Oh my God, this tree feels awesome! Oh my God, it's Miss July!'
""The hallucinations were so bad. It's the perfect anti-drug book because the hallucinations were unreal.""
She tells U.S. news show Access Hollywood Live the pills were supplied by the girls' yoga instructor, who was hoping to get lucky after handing out rave drug Ecstasy.
McCarthy explains, ""It didn't work out. We took so many we thought he was trying to kill us; we were running away from him.
""All of us were naked, although we were used to being naked, we couldn't find our clothes and eventually (we) walked back down the highway and got back home.""