Emily, a 24-year-old burlesque dancer with creamy skin and dark curly hair was at a party in Manhattan a few summers back when she lost her vagina. It was a worrisome feeling. She ran around the crowded loft frantically looking under bags and coats yelling, “I’ve lost my vagina!”

“Where did you see it last?” asked one friend with a laugh.

“Do you have insurance on it?” wondered another.

But Emily wasn’t kidding. She could feel the tears welling up, at which point her date, a longtime friend, walked by and snapped his fingers. She dropped an armload of coats.

“Never mind, you guys,” she said. “I found it!” Disaster averted.

Emily laughed as she retold the story on a chilly day in McCarren Park. But she could still revisit the sense of panic she’d felt, the result of an experiment with erotic hypnosis. Now, she’s become a practitioner of hypnosis herself.

My own interest in the subject started where basically everything does, online. I clicked something, and something else, and soon I was knee-deep in YouTube videos of Eastern European models entranced by men in bowling shirts, hypnosis blogs (Emily is one such blogger) and forums filled with arguments about proper technique. From what I could gather, erotic hypnosis is a fetish, but if its proponents are right, it is also a new form of sex—safe, certainly, but also dangerous-seeming in its own way. Under hypnosis, it was claimed, a subject could achieve a climax without being touched at all. It sounded a little like Erica Jong’s “zipless fuck,” but better. Sex without the muss or fuss, or, for that matter, the pregnancies, STDs or awkward goodbyes. It’s also a twist on BDSM, an expression of sexual power and submission at its most extreme.

On Fet-Life (a “kinky” social networking service), there are 12,490 people who are “Into” or “Curious about” erotic hypnosis—a one-click function similar to the Facebook “like” button. The Hypnosis New York group has 324 members and hosts monthly four-hour meetings.

Arriving at the prescribed location, a rehearsal space in Tribeca, I approached the receptionist. She looked like an actress. “I am here for erotic hypnosis,” I said, trying to articulate clearly, but not too clearly. She motioned to a cluster of cargo shorts and wiry hair, mostly male. My classmates looked like they might have been to ComicCon, which shouldn’t be surprising, since mind control is such a favorite technique of superheroes (and supervillains). They seemed to be staring at me, perhaps surprised to see a young new female student and wondering, since I was flying solo, whether I might be a potential homework partner.

Or maybe they were already trying to make me come? Yikes! If so, it didn’t seem to be working … or?

Nope, not yet.

We filed into a small room, and quietly sat in folding chairs.

When the speaker, Lee Harrington, arrived a few minutes later, I felt relieved. He looked not unlike a doll I had as a child called “Earring Magic Ken” (the doll was attacked by family groups for looking homosexual). Later, Mr. Harrington let us know he was transsexual, female to male, and that while living as a woman, he was a well-known porn star. He also indicated he dates men. (Maybe there was more to Ken than met the eye, too.)

Mr. Harrington stood in front of a white-board. “So when we think of erotic hypnosis, what do we want to do with it?” he asked.

“I wanna enhance the experience,” replied a man with a handle-bar mustache and a Long Island accent, crossing his arms.

Excitedly, Mr. Harrington explained that with erotic hypnosis you can make your partners believe they are more aroused than they are, you can lower inhibitions—get them to do oral if they don’t like it, or try anal if they are scared. Hell, if this caught on, the makers of Viagra and Cialis—not to mention the Internet spam industry—would be out of business.

“What else do people want to do with hypnosis?” Mr. Harrington asked the group. A large, blinking girl beside me cleared her throat. “It is fun to give people body parts that they don’t have in real life,” she said, pushing at her glasses.

“We could have someone who is an innie fully experience what it is like to be an outie,” he said, a reference to genitals (though it could almost definitely work with belly buttons, as well). “We could have someone jack-off their astral phallus. We could give someone a tail, or a set of angel wings!” Mr. Harrington went on. Anything is possible under hypnosis, he explained: tentacled alien gang-bangs, orgies with hundreds of men. Still, you had to be careful. Speaking from personal experience as a trans person, he warned, “It can be traumatic to give someone the genitals they wish they had and then take them away.”

The group brainstormed other things you could do, like allowing a trans person to experience each birthday in the gender of their choice.