There was Ted, an aspiring James Taylor type; Jason, an aspiring TV editor, who occasionally played fiddle to Ted’s guitar; Subieta, a friend of Jason’s from his hometown of Iowa City; and Mr. Mellitz, a film editor by training who plays lots of video games. The friends had met at New York University and are now in their early 30s. An eating-drinking challenge ensued.

“We each had $20 on the event,” said Jason. An eating-drinking challenge was not the only activity on offer in Mr. Mellitz’ palace of 21^st-century delights: board games, video games, weed, booze, music, a wall of movies to choose from and lots of snacks kept fresh with chip clips. Mr. Mellitz is an excellent host, he strives to keep his guest adequately stimulated.

“We each ate one raw egg in a shot glass,” Jason said, “drank three Tequizas, and one straight shot of tequila. I won easily, but then puked, which voided my win and gave the victory to Subieta.”

Later on, Jason and Subieta decided to take their bro session to the streets. It was a walk Jason will never forget: “We were standing on a corner, he points out a woman walking by and says, ‘One.’”

“‘What?’” Jason recalls asking. “Subieta says, ‘She’s a one. One means you would have sex with her, zero is you wouldn’t.’ And I said, ‘But that woman had no hair.’”

Subieta explained that the One, Zero game assumes a vacuum: no real-world repercussions, no one would know, you never have to see the girl again, the works. In a vacuum: Would you or wouldn’t you? One or zero? A scale with no room for nuance, no room for bullshit, no room for gazing at the moon. A cold and beautiful and terrible measure of a man’s private need.

“I said, ‘Oh, well, if you put it that way, sure, she’s a one.’” Jason remembers becoming “immediately fascinated” by the One, Zero. “I mean, it’s such a simple system, but Subieta took specific pride in picking the girls who were right on the cusp on the scale.”

Jason told Ted about the game, who immediately recognized its potential. Seven years later, Ted, now 32, is still a proud practitioner of the One, Zero.

“It really kills the time,” Ted explained. “You get a lot of giggles, and you get a lot of controversy. You have to remind people that it’s in a vacuum and force them to admit when they’re lying about their One, Zero scale.”

“Saying ‘one’ about a passing model is kind of considered bad form and like obvious and like shut up,” he continued. “The game only gets interesting when it’s borderline. Saying ‘zero’ about, say, a woman in a wheelchair—also bad form.”

Ted said that while the still dominant 1-10 scale of rating women was childish and gross and relied on silly objective standards, the binary scale was innocent, fun and revealed more about the assessor than the assessed. It allows for a certain honesty, because, as Mr. Mellitz put it: “There’s no real explanation necessary. You know you don’t have to go into detail.”

“It’s also completely universal and can be taught to anyone in 10 seconds,” said the singer-songwriter, whose affinity for the One, Zero has clearly yet to wane. “It’s universally easy to play and”—he chuckled—“it’s a great way to get to know people.”

The origins of the One, Zero are hard to pin down, but my research indicates that the binary scale, as it is also commonly referred to, made its debut around the turn of the century. A 25-year-old newspaper reporter friend of mine remembers when the One, Zero swept through the fraternity scene at Dartmouth. “If you mentioned binary scale to any of my friends, they would immediately know you were talking about girls,” he said. “It was common practice in frat basements. Dartmouth as a school—well, there was not exactly an astounding amount of talent—so it was never, ‘Was she hot?’ It was, ‘Well, was she a one or a zero?’”

Ricky Van Veen, 28-year-old co-founder of CollegeHumor.com, recalls hearing about the One, Zero sometime in the last five years. His own friends found little use for the system. “One or zero has to be the most barbaric way of describing another human being,” he said, a tad prissily. Instead, he said, he much prefers the “World with no sevens” scale his friend Mo Koyfman introduced him to, and which continues to be of use when the boys go out to dinner and attempt to describe girls to each other.

“There’s a big difference between a six and an eight,” said Mr. Van Veen.

Maxim magazine entertainment editor Patrick Carone, 32, says he first heard of the binary scale fairly recently. “It came after ‘wingman,’ so certainly in the post-Swingers era,” he said.

“I never really subscribed to it too much, because it’s too black and white. It doesn’t leave room for nuance,” said Mr. Carone, who remains a traditional 1-10 man. “I feel like if I had that in my mind, it wouldn’t be fruitful—you want to have a bit of a range of your interest level in this girl; otherwise, it might close you off too quickly or make you jump right in there too quickly.

“The 1-10 spectrum,” he went on, “even if ultimately it’s the same result, if you think about things in more of a range, I think then you’ll take more aspects of her into account, like personality.”

Moreover, he claimed, “I think the One, Zero works in theory—but not in reality.”

Ted recalled that a few years back he tried to introduce the game to his stepdad during an early stepdad-stepson bonding night at a bar in San Francisco. “He said that he had spent 30 years training as a Zen Buddhist to not have judgments like that,” said Ted. “So he couldn’t play.”

Ted noted that he can get an accurate read on his pal Jason’s mood—which is often hard to decipher—depending on how generous Jason was being with his ones. Also: “Sometimes people really surprise you. You don’t really know a guy too much, and he’s throwing out ones to a bunch of girls you might not expect him to, and you kind of get a little glimpse into his mind.”

Guy Mellitz concurs: “It’s kind of fun when you’re walking down the street with your buddy and you pass a girl or two and all you have to say is ‘one’ or ‘zero.’ A lot of times, one guy says, ‘One,’ and the other guy will say, ‘Yep,’ or hold up a finger,” said Mr. Mellitz. “It’s also eye-opening in terms of how you see your friends, because you sort of learn something about your friends when you have differing opinions. A guy will throw out a one and you’re like, ‘Really? Huh. She was a zero for me.’ It’s like, O.K., I understand you a little bit more now.’”

Indeed, only a few years after the friends adopted it, the game would provide a window into the deep turmoil going on in the mind of Mr. Mellitz.

“Guy was in a really bad relationship with a terribly unattractive girl,” said Ted. “And when he started throwing out zeros to girls who were much more attractive than his girlfriend, I got the sense that he was just mad at boy-girl relationships in general and had absolutely no context for anything.”

Despite its purported innocence, Ted, Jason and Guy know better than to play One, Zero in front of women. Especially after witnessing what happened with their friend Paul Lovelace and his girlfriend at a Brooklyn bar.

“Lovelace’s girlfriend started playing it for a while, and that really fucked things up,” Ted said. “The two of them were playing some mind games with each other. It was a sort of rough patch in their relationship. So Paul would pretend it wasn’t a big deal to play One, Zero around his girlfriend. And so she rebutted with starting to play it herself at bars. She’d be like, ‘Yeah, he’s a one.’”

I called up Mr. Lovelace, who is a documentary filmmaker living on the Upper West Side. He said that One, Zero was never the cause of any friction between himself and the girlfriend, now his wife. He added they continue to play the game in social situations.

Anna Holmes, editor of the women’s blog Jezebel, said that she did not know of any codified rating systems used by women on men. Nor had she ever witnessed a group of adult women sitting around ranking the men that pass by, adding that the episode of Sex and the City in which the sassy gals are seated at a cafe playing “would you, wouldn’t you” was bogus.

I apprised Mrs. Holmes of the many scales I had discovered in just a few phone calls.

“The only people it really hurts are the people who are engaging in it themselves,” she said. “They’re just slow growers. … New York allows for a prolonged adolescence in which people are allowed to behave like 16-year-olds into their early 30s.”

“I think [rating women] is always going to be present in males,” said Mr. Van Veen. “I’m 28 and I don’t see it slowing down. I think females are also going to rate males. I can’t see women doing the binary scale as much as guys. Maybe I’m giving too much credit toward females, but I just can’t imagine girls sitting around going, ‘Zero!’ ‘One!’”

I needed some help; I called the great Tom Wolfe.

“Binary is pretty masculine,” Mr. Wolfe told me. “Because men are not terribly bright in this area; their entire intelligence is below the belt buckle. Whereas women seem to be actually interested in what a man does, how much money he has, where he went to school. The binary system’s not primitive, but men are primitive. Man sees the mission. Women see the whole picture.”

Last Sunday morning, Mr. Mellitz was in his kitchen washing dishes, while his present girlfriend, Myrna, was lounging on the couch.

“Yep,” he called out over the faucet, indicating he was still a proud One, Zero practitioner. Myrna said she didn’t mind. The couple met on match.com last year. From the couch Myrna gushed that Mr. Mellitz had on pajama bottoms, a tight-fitting Pixies shirt and a nice, thick stubble, just the way she likes it. “He’s a solid nine,” she said. 

But surely, one has to suspect, he’d prefer being a one.

smorgan@observer.com