The co-founder of a Silicon Valley tech firm called a female employee into his office and allegedly dropped his pants — then fired her when she rejected his sexual advances, according to a bombshell lawsuit.

Robert “Elliot” English, of the artificial intelligence startup Pilot AI Labs, began bombarding 24-year-old director Rachel Moore with “sexually inappropriate” comments about her buttocks and “F–k me” boots shortly after she was hired in spring 2017, according to the suit, filed Wednesday in San Francisco County Superior Court.

English, along with CEO Jonathan Su, allegedly spoke in graphic detail about subjects such as pornography and bragged about their own sexual conquests while on the job, according to the lawsuit.

“On one occasion, English told [Moore] that he participated in an anal sex workshop at the Burning Man [festival] led by a famous porn star,” Moore, a recent Stanford University master’s grad, says in the suit.

She also learned that male employees watched porn in the workplace — and that the office had a “designated server area for masturbation,” according to the lawsuit.

“An intimate knowledge of the porn industry and lingo appeared to be a job requirement,” court papers state.

To fit in, she went along with the “sexually charged” office culture, joined some of the conversations and was rewarded with a $20,000 raise, according to the lawsuit.

“[Her bosses] began taking her more seriously and including her in more in important projects and [she] became one of their ‘buddies,’” the lawsuit states. “When [she] didn’t reciprocate … English and Su tended to ignore her and not take her seriously.”

But English’s crude behavior got worse.

In December, English allegedly called her into his office, shut the door and removed his pants — then began whining about his ex-girlfriend’s flaws, Moore claims, according to the paper.

She told her boss she considered the move harassment and tried to bolt — but he wouldn’t let her, she claims. Eventually she got out but later paid the price for rejecting his advances, the suit states.

“She started to be criticized for things like not taking good notes, being ‘too emotional,’ not being a good enough ‘cheerleader,’ and not being understanding enough of English’s sexual frustrations,” according to court papers.

“[It] intensified to the point at which her ability to perform her basic job duties was seriously impaired,” Moore claims.

She reported her boss’ creepy move to Su — who defended him by saying he was simply “sexually frustrated,” according to the lawsuit. Su allegedly took no steps to investigate “the pants dropping.”

When she later turned down Su’s request that she go on a dinner date with English, the company stopped paying her — and cut off her access to the firm’s computers, according to the suit.

She is now suing for unspecified damages over the “crude and graphic sexual harassment.”

Pilot AI Labs didn’t respond to a request for comment immediately Friday.