As college administrators become more accommodating of easily-offended students, one formerly uncontroversial tradition is now a yearly battle in the war over political correctness on campus: Halloween.

Tis the season, unfortunately: universities across the country are busy warning students that even mild-seeming costumes could be construed as inappropriate, or worse, culturally insensitive. And while most college administrators know they can’t actually tell students what to wear on the night of October 31, implied threats—of misconduct violations, harassment charges, even police investigations—abound.

Take Tufts University, where student-leaders of Greek life on campus are particularly worried about costume-related sanctions. They have good reason to be concerned: the university is watching.

“We encourage all students that feel like they have encountered someone who is wearing an inappropriate and offensive costume to please file a report,” said Dean of Students Mary Pat McMahon, according to a letter sent to the Greek community.

This is not an empty threat. According to the dean, “offensive” conduct could trigger an investigation by campus police.

What kinds of costumes could possibly be so offensive that they merit police involvement? Wear one, and find out.

Greek leaders would like to err on the side of caution—how’s that for Halloween spirit?—and have asked members of their community to eschew “inappropriate, offensive, and appropriative costumes.” Cultural appropriation—dressing up like someone from a different race—is especially frowned upon. But that’s not all: costumes “relating to tragedy, controversy, or acts of violence” are also frowned upon.

One wonders what’s left. Many students who heed the above guidelines are presumably restricted from dressing up as samurais, hombres, geishas, belly dancers, Vikings, ninjas, rajas, French maids, Bollywood dancers, Rastafarians, Pocahontas, Aladdin, Zorro, or Thor.

Garden-variety Halloween costumes—vampires, zombies, etc.—would seem to run afoul of the prohibition on “tragedy and acts of violence.” And this year’s topical costumes—Harambe, Cecil the Lion, Donald Trump—invoke controversy, so they’re out, too.

Tufts is not alone in its quest to sanitize Halloween. The University of Massachusetts-Amherst recently launched an initiative—carried out by UMass’s Center for Women and Community, Center for Multicultural Advancement and Student Success, and the Stonewall Center—to make students more aware of the damage a Halloween costume can do. The groups plastered campus with flyers urging students not to dress outside their race.

One student even posted a “threat level meter,” designed to warn students about the potential for a given costume to offend. “Does your costume… significantly change the shape of your eyes, nose, lips, or other facial features?” If so, a student runs an “elevated” risk of offending someone, according to the assessment’s creator, Wall Street Journal ‘Tao Jones’ columnist Jeff Yang. The assessment deliberately mimics Homeland Security’s color-coded terror threat-levels, which speaks volumes about how seriously the PC-costume-enforcement crowd takes its mission.

Indeed, a spokesperson for UMass-Amherst conceded that the posting of the threat assessment level went too far.

“It is not part of the recommended educational materials that RAs were advised to display,” university spokesperson Edward Blaguszewski wrote in an email to The Daily Beast. “The chart has been removed from the bulletin board.”

Blaguszewski stressed that UMass-Amherst “does not prohibit or ban any costumes.”

You would forgive students for being confused. After all, this is the university whose residential advisors apparently thought they were required to prohibit students from making jokes about Harambe, the deceased gorilla and internet meme. RAs went as far as to suggest (wrongly) that the popular catchphrase “dicks out for Harambe” was a violation of Title IX, the federal statute prohibiting sex-based discrimination in higher education.

No campus is more famous for its costume crackdown than Yale University. Last year, a university-wide email urging students to be mindful about their wardrobe choices irked a professor, Erika Christakis, who objected to the administration instructing students how to dress. She followed up with her own mass-email stressing free expression and personal responsibility. That email infuriated certain activist students on campus, who surrounded her husband—Yale’s Silliman College Master Nicholas Christakis—and demanded both their resignations. (The Christakises eventually left their administrative positions, though Nicholas is still teaching.)

Having been roundly criticized for its infantilizing treatment of students, Yale is treading more carefully this year, telling students only to “stay safe” and make good choices.

Other universities are undeterred in their quest to ruin Halloween. The University of Florida offers 24/7 counselling for students who are traumatized by offensive Halloween costumes, and encourages victims—of costumes!—to file a report. The University of Wisconsin-La Crosse opted for the carrot, offering an educational seminar about dressing responsibly. But it also wields the stick.

Universities are within their rights to educate students about their costume choices, although those conversations should probably be handled by professors with some specialization in the subject rather than administrators who wield the power of formal punishment. But I can’t help but wonder whether colleges are killing the spirit of the holiday. If everyone is obligated to dress up as someone or something closely related to their own racial heritage, well, what’s the point? We can all just be ourselves for Halloween.

But Halloween is supposed to be a little subversive, isn’t it? Well-intentioned mischief is built into the holiday. Have college administrators ever heard of the Rocky Horror Picture Show? Have they heard of drag shows, where participants enthusiastically appropriate the dress and mannerisms of another gender? We’re defining harassment far too broadly if we’re giving students license to complain that infrequent, transgressive revelry rubs them the wrong way.

I can understand why students might take offense at blackface, which has a specific, racist historical context. But there’s nothing intrinsically evil about pretending to be someone else for one day of the year, especially if the costume isn’t intended to disparage or mock anyone’s ethnicity. Shouldn’t the default position of an enlightened populace be that culture is fluid and belongs to no one, that we are all individuals with the license to explore our interests, and that everyone should be encouraged to briefly appropriate the most interesting aspects of any culture to which they are drawn?

Author Lionel Shriver put it best. Speaking before the attendees of the Brisbane Writers Festival—and wearing a tiny Mexican sombrero to boot—she said, “I am hopeful that the concept of ‘cultural appropriation’ is a passing fad: people with different backgrounds rubbing up against each other and exchanging ideas and practices is self-evidently one of the most productive, fascinating aspects of modern urban life.”

There’s nothing scarier than the idea that college campuses are no longer places where students are free to express themselves without fear of institutional reprisal—especially on the one day of the year when it’s supposed to be okay to be someone else.