The pop icon, 56, spoke to Billboard recently and when asked if she'd read the book, she said, "Yes, I have. It's pulp fiction. It's not very sexy, maybe for someone who has never had sex before."
In fact, Madonna said she kept reading the book and couldn't understand what everyone was so excited about.
"I kept waiting for something exciting and crazy to happen in that red room thing, and I was like, 'Hmm, a lot of spanking,'" she added.
She's also doesn't think the storyline is very believable.
"I also thought, 'This is so unrealistic because no guy goes down on a girl that much,'" she said. "I'm sorry, but no one ... as much as the guy in that book."
The "Rebel Heart" singer added that for her "sex is a wonderful, necessary part of life."