It is not easy to scare people on Halloween these days. In 2014, rivers of blood course through network television; serial killers have been downgraded from stomach-churning monsters to TV bad boys; and the public is bombarded with zombie movies, vampire novels, and CNN Ebola updates. A mask of The Scream just isn’t going to cut it.

But there is one image that retains the power to terrify: A boy dressed as a girl.

Every year, about this time, the Internet buzzes with parental panic: My boy wants to be a princess—or Daphne from Scooby Doo or Wendy from Peter Pan—what should I do? Would you let your son be Frozen’s Elsa for Halloween? Care.com reports that 65 percent of people it surveyed (1,654 out of a total of 2,548) said “no” to letting a boy wear a princess costume.* Or, as a CaféMom commenter put it, “NO WAY AND HE WOULDN’T WANT TO ANYWAY.”

I wish I could dismiss the horror-struck momosphere with sympathetic condescension—man, it must be hard to live in a red state—but I can’t. My dining room table is a progressive enclave within a liberal bastion within the state of New York, and yet, it was there that my 5-year-old son’s declaration that he wanted to be Wonder Woman for Halloween was met with the shocked gasps and nervous laughter of our dinner guests. No one spoke. And then a friend—trembling but determined, like the one kid in the horror movie brave enough to move toward the scary sound behind the door—ventured, “Wouldn’t you rather be Spiderman?”

A couple of years ago, ABC News did an installment of What Would You Do? in which they staged an argument between a mom and a son in a costume store. The son wanted to be a princess; the mom said “no.” And the other customers helpfully tried to give him ideas of things he could be—policeman, firefighter, ninja—while agreeing with the fake mom that she should “nip it in the bud.”

But what is “it” and why does it need to be nipped?

Why are grown-ups so terrified by the thought of a boy in a Belle costume? Do they take literally the expression, “What are you going to be for Halloween?” Do they, missing some fundamental understanding of the concept of costume, believe that if you dress as a girl, you’ll stick that way?

No one appears concerned that, say, a child who dresses as a yellow crayon will be consigned to a life of monochromatic coloring. Or that a child in an alien costume will ultimately have to return to the home planet. There are no feverish blog posts along the lines of Should I let my son dress as a Martian? Children are regularly permitted—even encouraged—to dress as zombies, spiders, and Rubik’s cubes. Which means, I guess, that if you’re a boy, it’s worse to become a girl than … pretty much anything.

If people aren’t actually afraid that wearing a dress could turn a boy into a girl, perhaps they fear that it could make a boy gay. You know, the way wearing a football uniform makes you straight. Granted, it seems unlikely—it’s 2014, and “Born This Way” seems fairly well-established—but as a careful reader, I think I can detect a hint of old-fashioned homophobia in Facebook comments like, “If u want them to be gay then go right a head.”

Some claim not to let their boys wear girl costumes simply to protect them—from bullying, from a bad reputation, from “gender confusion.” They might even scoff at the idea that clothes determine sexual orientation … while secretly believing that clothes reveal it. That their boy is dressing as a girl for the day because he really wants to dress as a girl all the time and Halloween is his one chance to go full Elsa. Of course, there’s nothing wrong with being gay—as long as it’s someone else’s kid.

My son did not, in the end, go full Wonder Woman that Halloween. He decided on Batman. It turns out that his annual Halloween ambition is not to frighten, but to ingratiate. He once told a succession of neighboring homeowners that they each had the best Halloween decorations on the street. When he dressed as a Miami Dolphin he told all the Giants fans that the Giants were his second favorite team, and mysteriously ended up with more candy than either of his younger siblings.

As someone who believes Halloween should be about terror, not Twix, I feel that my son—leaving his Wonder Woman costume in the toy bin, never wearing in public the skirt he got for his fifth birthday—missed a big opportunity. An opportunity my daughter, for one, will never have. Girl-dressed-as-boy is just not scary. On top of which, it’s actually very difficult for a girl to dress as a boy: when a girl dresses as Batman or Han Solo, she is dressing up as the main character, the hero. Whereas when her brother wants to be Pepper Potts or Princess Leia, well that’s obviously just frightening.

Maybe when enough popular heroes are female, then we won’t see their femaleness as their primary characteristic. I’m pretty sure that when choosing his favorite character from the Justice League, my son was thinking not boobs vs. pecs but invisible plane vs. Batmobile. Enough female heroes—hell, enough female characters with character—and maybe grown-ups will be able to think that way, too.

Until then, as a society, we will continue suffer from a pervasive irrational fear that we can neither fully explain nor entirely squelch. So tonight, boys, if you really want to scare the crap out of your neighbors, you know what to do. Might I recommend something in pink tulle with a sweetheart neckline?

Correction, Nov. 1, 2014: This article originally misstated that people answering a Care.com survey said “no” to letting a boy wear a “girl” costume. They said no to letting a boy wear a princess costume. Also, this article has been updated with the number of people who responded to the Care.com survey. (Return.)