When Melissa, 26, was a student at Rutgers, she’d frequently get invited to parties, mostly put on by fraternities, with themes like “CEOs and corporate hoes.”

She says she can still remember “running around campus on a brisk New Jersey November in too-tall cheap heels and a skirt that kept riding up past the curve of my bum without a coat, [all the while] looking at the men walking calmly in their pants, flats, and thick sweaters.” (I contacted five of the fraternities that Melissa mentioned threw parties like this to ask about their decision-making but none of them got back to me.)

College groups that throw gendered theme parties typically believe they’re just being silly and playful. But for many, these events sexualize women and exclude those who either identify outside the gender binary or simply don’t conform to gender roles.

Carolyn, 23, similarly remembers “office hoes and CEOs” parties at the University of Oregon. “The boys were just looking for freshman girls in slutty clothes to get drunk and dance or make out with,” she says.

Zach, 36, was in a fraternity that prided itself on being “more gentleman-like,” but it still threw parties including “CEOs and executive hoes” and “golf pros, tennis hoes.” He also remembers another fraternity hosting “Playboy parties.”

“It was their aspiration to live like Hugh Hefner for a night,” he remembers. “Essentially, they’d invite sororities with a heavy suggestion of lingerie outfits.”

Lisa Wade, professor of sociology at Occidental College, heard many students mention theme parties in research for her book “American Hookup.” “There are basically websites for fraternities giving them ideas, themes like that: CEOs and office hoes or pimps and hoes,” she says. One student she interviewed even talked about a “perverts and underaged girls” party.

“All of these have a really clear power dynamic,” Wade points out. “[Such themes] specifically place men and women into unequal relationships.” Namely, the women are expected to dress sexy, while the men are supposed to wear something symbolic or silly or not dress up at all.

Men’s approval is the currency at these parties because men have the resources

“It makes it very clear that when a party is thrown, it’s women who are supposed to bring the sexiness to that party,” Wade explains. This puts women in situations where they have to compete with other women, and they face judgment and social exclusion if they’re not “sexy” enough. It also gives men the power to be the judges.

“There’s a subconscious dominance — men’s approval is the currency at these parties because men have the resources,” Wade says. For example, Wade found in her research that men are often the ones serving alcohol or deciding who gets into after-parties. This is arguably in large part because the national association that governs most U.S. fraternities allows alcohol in chapter houses, while the organization overseeing most U.S. sororities does not. When women are expected to dress sexy, their access to these resources becomes dependent on their sexiness.

Another issue that frequently comes up at college theme parties is racism. Wade has heard of themes such as “colonial bros and Navajos.” LGBTQ activist S. Bear Bergman, who frequently works with college students, often hears of white students dressing up as an entire cultural group, like Indians or Mexicans, which inevitably ends up perpetuating racial stereotypes.

And, as if it couldn’t get worse, female racialized costumes are usually something along the lines of “sexy Indian” or “sexy Mexican.” Some themes, like Tiki party, outright encourage racism or cultural appropriation, points out social worker and activist Aida Manduley.

Theme parties are also frequently transphobic. Emily, 40, went to a “Transvestite Night” party at Bennington College, where people were encouraged to dress up as the opposite gender. Even when they’re not that explicit about it, gendered theme parties can exclude trans and non-binary people. “When spaces have binary-gendered themes, it can be deeply alienating and exclusionary to non-binary individuals — or trans folks who aren’t yet out and may feel forced to adopt a gender presentation that doesn’t actually fit them,” says Manduley.

To minimize sexist parties and other gendered power dynamics on college campuses, some schools have cracked down on single-gender groups, Wade says. Harvard has forced its finals clubs to integrate, for example, and Princeton has done the same with its eating clubs.

But all student groups, coed or single-gender, can make a point to host parties with gender-neutral themes, says Bergman. “Why have a costume party with a theme that you 100 percent know is going to induce people to make terrible choices about their costumes? Have a disco party. There are other choices.”

That’s what Melissa’s sorority did. “Rather than degrading themes, we picked Instagram-friendly, weather-appropriate themes that we wanted to dress to,” she says. Her favorites were pajamas, Candyland, and Olympics. As a member of a coed fraternity in college, Manduley helped throw parties with themes like the Irrational Party, Seeing Double, and Fire and Ice.

“Whenever planning a party theme, asking oneself the following questions may be helpful: How does this send out messages about race, gender, sexuality, class, etc.? How may that exclude some people? How may that erase others?” says Manduley.

But according to Bergman, the bigger problem is that students are not adequately educated about issues like gender, race, and sexuality, which leaves them unaware when they’re making insensitive decisions regarding party themes and costumes.

“Theme parties that reinforce gender norms are a symptom of a larger issue; they’re both a reflection and a continuation of social messages at large,” Manduley explains. “Just look at a rack of Halloween costumes — mostly gendered, and in such ways that hypersexualize women and make men look powerful or goofy. Beyond providing more ideas and concepts for theme parties, we must interrogate how other campus spaces and policies contribute to gendered norms.”