Katherine Losse had just dropped out of grad school at Johns Hopkins when she moved to Palo Alto and was hired as Facebook employee No. 51. She joined the Customer Support Team, answering questions like “What is a poke?” When she arrived, she found a fraternity full of immature and sexually inappropriate behavior. In her new tell-all book, The Boy Kings: A Journey Into the Heart of the Social Network, Losse dishes on the culture that drove the website that changed our daily lives. From Mark Zuckerberg forcing all female employees to wear a shirt with his face on it to co-workers wanting to “put my teeth in your ass,” here are some of the juiciest bits from the book.

The Really Graphic Painting

Losse joined Facebook in 2005, working in customer relations. She remembers her first day there:

Much of the graffiti in the room featured stylized women bursting from small tops that tapered down to tiny waists, mimicking the proportions of female videogame characters. It seemed juvenile, but I wasn’t very bothered—it seemed like the kind of thing that suburban boys from Harvard would think was urban and cool. “We had to move the really graphic painting to the men’s bathroom because someone complained,” an engineer told me as he gave me a tour of the tiny office.

Zuckerberg’s Vision

Mark Zuckerberg had a grand and also vague vision for Facebook. “I just want to create information flow,” he would say. The idea was too general to disagree with, and “we knew that we weren’t supposed to disagree.” He would end meetings by saying either “domination” or “revolution.”

Zuckerberg’s Inappropriate Photo

In 2006 the company went to Lake Tahoe for a winter getaway. After some cheap Trader Joe’s wine and impromptu karaoke, Losse donned a bearskin—complete with bear head—that adorned the banister in the cabin. The builder of the Photos app naturally took pictures. And in one of them:

Mark is gesturing at me haughtily like an emperor as I stand doubled over in laughter with the bear suit draped over me. It was all innocent fun; everyone was laughing and enjoying themselves, but when I saw the photograph appear in a Facebook album that Monday I was struck by the loaded nature of the image, ripe for interpretation, in which Mark appeared to be commanding a female employee to submit.

The photo appeared on Gawker four years later with the caption, “This one also might lead the confused and bewildered to conclude that Mark Zuckerberg got drunk in Lake Tahoe and taunted a co-worker.” Losse says it didn’t occur to anyone that there was anything wrong with posting the photo on Facebook.

More Zuckerberg Immaturity

Zuckerberg, Losse says, wrote on his business card, “I’m CEO, bitch.” When a female employee reported that a male co-worker in the lunch line said, “I want to put my teeth in your ass,” Zuckerberg responded in a meeting, “What does that even mean?”

I Heart Zuck

“On Mark’s birthday, in May 2006, I received an email from his administrative assistant telling me that it would be my job that day, along with all the other women in the office, to wear a T-shirt with Mark’s picture on it.” The men, on the other hand, were told they would be wearing Adidas sandals all day. “The gender coding was clear: women were to declare allegiance to Mark, and men were to become Mark.”

Nightclub Women ‘Not Pretty Enough’

During a trip to Las Vegas, “the boys” were at Caesar’s Pure nightclub. But instead of chatting up and kissing girls, they rejected the women the bouncers had brought to their table. “‘Leave! You’re not pretty enough!’ one of them seemed to say over the din of the club as he shooed the girls away in succession like so many servants.”

Sheryl Sandberg to the Rescue

Good thing Sheryl Sandberg, the company’s COO, has been named to the board of directors, becoming the first female among seven white guys. Losse portrays her as someone who has been an advocate for women in Silicon Valley. When Sandberg came on board, Losse went to her with horror stories about two men in her department. “I didn’t hear back immediately about any of the issues I had raised with her, until she stopped briefly by my desk one day a few months later and in the low, succinct office voice that she mastered, said, ‘I just want you to know that the situations you told me about have both been handled.’ I had heard nothing about it. ‘You see, I’m so good that I make things happen and no one even knows about them,’ she said with a smile. Sure enough, the manager who propositioned employees had been subtly demoted and the aggressive engineer moved to another team.”