A few months ago, a friend told a juicy story about another friend’s hookup with a male pop star. “She said she was on her period, and he said he was into it. Like, it’s his thing.” The story involved period blood all over the musician’s face and the menstrual version of a shit-eating grin. “Ewwww,” I squealed in titillated terror as my friend added, “But that’s a thing, right? Guys who are into periods?” Not just okay with sex during menstruation, but actively seeking and looking forward to it.

At the time, I was skeptical. But after quizzing friends, strangers, and a few experts on the subject, I can now confirm that “into periods” is most definitely “a thing,” for men and women both. Some reasons are physical and hormonal; others practical; and many more are tied to erotic associations and pride in reveling in the uncensored female body. In men, such pride is a modern sort of machismo, one defined by hardcore connoisseurship — much like a chest-thumping dude-foodie who develops a taste for offal. Menstruation is, well, gross. It can irreparably damage your upholstery. It is made of a substance that causes people to faint on sight. Thus, menstrual sex is an advanced maneuver, available only to men and women with seasoned sexual palates and hangup-free psyches. As Louis C.K. put it in his famed mockery of menses-averse young men, “Fuck her in the period hole, you idiot, what’s the dilemma? I don’t give a shit, if you’re having your period, come on over. I’m 41, I’ll fuck the shit out of you, I’ll drink the blood, let’s party.”

My friend Daniela echoed this sentiment. “A real man goes down on you on your period. And loves it,” she wrote in an email. Sexual naifs fear encounters; those with experience cannot be fazed. “And you love it, too. The vag is much more sensitive when you’re menstruating,” Daniela continued.

For some, menstrual sex isn’t a dirty necessity for the desperately horny; it’s an activity to spend the whole month awaiting, with glee. Another female acquaintance described “an indie actor who would only fuck me on my period,” and “an art director who was obsessed with tampons as a prop.” The latter evokes an unfortunate echo of one model’s allegations against the photographer Terry Richardson: “I politely declined his offer to make tea out of my bloody cunt plug,” Jamie Peck wrote of Richardson’s request to “play with” her tampon during a photo shoot.

But period attraction is not only for perverse celebrities. A friend we’ll call Maya once had a long-distance boyfriend, whom we’ll call David, who begged her to schedule visits during her period. “David wasn’t even a hippie,” she reflected in a Gchat. “This is a dude who wears Patek Philippe casually.” The first time they had period sex was the week before David moved cross country. “I’d been putting off my period by skipping the period week in my birth control for like four months at this point, because I knew he was moving but was so enamored by his giant dick that I couldn’t bear missing out before he left. But of course the week before he went, THE FLOOD OF A THOUSAND PERIODS is unleashed. It just broke through, like a scene from The Ten Commandments.” To her surprise, David was into it from day one, proclaiming the situation “hot” even as he emerged from sex smeared from waist to thigh in menstrual blood. “He said ‘the musk’ turned him on,” she recalled, a sensory note that I heard from more than one man. “The upside is all in the smell,” one straight man wrote in an email that he followed immediately with two frantically backpedaling emails as he panicked about revealing too much. Such is the double-edged sword of embracing a primal desire: Uncontrollability means the potential for sexual glory is high, but so too is the potential for humiliation.

Maya continued: “He made me stay at his place for, like, the next three days to capitalize on all the period sex. Like a newly caged feral animal. He ate me out A LOT. No tampon. I was like, ‘Why can’t I just keep a small tampon in?’ And he goes, get this, ‘The string grosses me out.’” When I asked if David’s face got messy, she replied with a link to a picture of a zombie with a bloody mouth. She didn’t enjoy the menstrual romp as much as David did: “It made me feel gross and guilty.”

Her squeamishness was something of a relief; I had begun to worry that I was the only Old Testament–style prude who still finds period sex distasteful. (Leviticus: “If there is a man who lies with a menstruous woman and uncovers her nakedness … both of them shall be cut off from among their people.” As one who tends to feels like a bloated wad of filth during her period, I mostly follow this rule.) But even period-sex enthusiasts, I discovered, can recoil from coagulated blood while reveling in menstruation’s sexual side effects. Daniela and several others spoke positively of menstrual cups and diaphragms, while others simply put up with ickiness in the name of hot sex. One blood-averse man described women who got very horny during their periods, and their arousal aroused him. The ability to trigger cascading orgasmic freak-outs, he said, was incentive enough to perform cunnilingus on vaginas that tasted “like very rare steak” and postcoital imagery he likened to “human carnage.” And though blood mixed with the fluids of sex can make a dramatically grim tableau, period sex need not require engagement with that much blood: “A standard sexual session for most couples is 5 to 15 minutes,” the sex therapist Vanessa Marin told me by email. “There’s not a ton of menstrual fluid that comes out during that time, period.” Still, Marin argued, even on a heavy-flow day menstrual blood could serve as — brace yourselves, Leviticans — “a natural lubricant.”

“I had P sex last night!” a thirtysomething friend wrote by email. “OMG felt SO good.” She hadn’t attempted it in years, mostly owing to an aversion to unnecessary laundry. “We didn’t put a towel down. That felt too uncivilized,” she said of her gallant return to menstrual fucking. “We didn’t last long, maybe ten minutes. Everything just felt tighter, and like there was more pressure and like an intense heartbeat in that area. I was also really sensitive everywhere, from my nipples to my ass. My orgasm was amazing. It was like this this MAJOR release — everything clamped up really tight and then released really powerfully. I was shocked at how different it all felt from ‘normal’ sex. And it didn’t make a mess at all. No blood on the dick even!”

Heightened female libido and pleasure, though not universal, is routinely associated with menstruation, Planned Parenthood medical spokeswoman Dr. Vanessa Cullins told me by phone. Increases in blood flow to the pelvic region could heighten pleasure, while surges in estrogen (at the start of the period) and lutenizing hormone (at the end) affect the sex drive. Additionally, a woman who thinks she can’t get pregnant may be “more relaxed.”

Though pregnancy is less likely during menstruation, the phenomenon is not unheard of. What’s more, the cervix is more open than usual during menstruation, which Cullins says means exposure to bacteria and STDs are more likely to develop into infection: “It’s very important to use a condom unless you’re supremely confident that you’re in a mutually monogamous relationship.”

Though Maya’s three days of menstrual good-bye sex were “really good,” she refused David’s request for menstrual visitation. The duo broke up a few months later, having never again had period sex. In retrospect, Maya believes her own insecurity held her back. She described her disgust at even acknowledging the word musk and the terror of seeing color-coded evidence of vaginal contact on the parts of his body he used to touch her. “The worst was when he’d text, ‘We haven’t had strawberries-and-cream sex in a while.’ DON’T RUIN DESSERT, DAVID.” Still, she wonders if she shouldn’t have held on to this man, the one who saw her in her messiest state and embraced it. The one who embraced the messiness of sex itself. “Really looked the gift-horse in his period-blood-covered mouth,” she said.

“He said it was sweet, like actually sugary-sweet,” she continued. “He also said every girl tasted different. Oh God, he’s done period-sex taste tests. Oh God. Oh God.” As she mashed the keyboard to express her distress, I did my best to comfort her. Don’t feel bad, I advised, you gave it a try but it wasn’t for you. Revulsion, like attraction, is uncontrollable sometimes.

