As a recent revealed, if youre like a lot of guys, you probably do some kind of nod-a subtle, some say instinctive nonverbal greeting you may not even be aware youre performing. Its a small, platonic gesture jam-packed with semiotic meaning-a sign of mutual respect, of friendly recognition, of acknowledging anothers presence without being too pushy.

Call it the Silent Sup.

Some guys seem to do it consciously as a way of communicating regard, diffusing tension, or simply saying hello without needing to stop and chat. Others may do it without even thinking about it, almost as a reflex. It can be done for the most seemingly mundane of reasons, like noticing that someone has the same headphones as you, or it can be done as a meaningful show of recognition and support, as is the case with some men of color who say they sometimes use a version of the nod to acknowledge one another in primarily white spaces. In any case, it can be a complicated gesture, one whose meaning can change for some based on the circumstances and the subtlest of nuances.

It makes you feel that theres a connection, body language expert Patti Wood told Mens Health by phone. This is a ritual you can do from a distance that still has some purpose to it.

Given the subtle nature of the Silent 'Sup, it would be completely understandable if you werent aware it was a thing. I hadnt given much thought to this oddity of male behavior until last week, when I saw a popular Reddit thread on /AskMen. It asked: "Why do we nod at each other when making eye contact with random dudes?

That simple query generated a massive response, as was the case when Men's Health deputy digital editor Jordyn Taylor posed a similar question on Twitter . The responses came flooding in-some from guys who said they do it, but can't put their finger on why.

lol I do this sometimes and I have no idea why - Keith Wagstaff (@Kwagstaff) February 22, 2019

Others, seeking to explain the phenomenon, suggested it's a simple nonverbal hello-and nothing more.

A nod is a hey whats up. So instead of saying it cause as you know men like to be nonverbal. We just nod - Terrence (@T3putts) February 22, 2019

But others viewed it as something deeper, a callback to some primal, animal instinct latent in men.

Every man sizes up every other dude in the room always. (Similar to women I think but not for same reason). A nod is a sign of respect (makes you equal) If a tiger or marauding band comes through, we got this shit. It 's primal! - Micah Gilchrist (@XPTmicah) February 22, 2019

Nodding at another man is like a combination of respect, and, frankly, disarmament, Adrian Fontes told Mens Health in a Twitter message. Because men are wired to fight each other, this simple gesture clears all tension and gives the other permission to relax.

According to Wood, theres something to both interpretations.

Sometimes, youre nodding to say, See you there, but I dont want to stop and have a conversation, she said. So instead of it being a signal that would indicate you want conversation...youre closing off deeper or more lengthy interaction.

But, Wood said, it can also be loaded with primordial symbolism-a desire, conscious or not, to convey alpha status. To protect your neck by either nodding downward or not nodding at all, she said, can indicate vulnerability. To nod upward, by contrast, can signal confidence and power.

If you watched a nature show, you would see this, she said.

In messages to Mens Health, guys echoed Woods assessments, suggesting this is more of a thing than wed previously thought, and that many men feel a great deal can be intuited from the gesture.

Its a subtle acknowledgment of: a) hey I know you, how's it going b) similar likes ie sports teams or the motorcycle riders c) kudos for being in the company of someone way out of your league in a dating situation all silent versions of Will Farrell and John C Riley pic.twitter.com/6DqYGgVu2f - Al Grant (@MrAlGrant) February 22, 2019

It's an acknowledgement that eye contact was made and all's cool. Watch closely, if one nods and the other does not, well, that probably means a vicious Kung Fu fight is about to break out. I do not know Kung Fu so I am very grateful that all my nods have been returned thus far. - David Hart (@real_davehart) February 22, 2019

Just yesterday I was going down the escalator as another guy was going up and he nodded AT me, but not TO me, and mouthed the words "nice shoes" so I said "Thanks! They're Cole Haan" and he was taken aback by my words."Oh, you saw what I said?" Weird, or maybe I am? - Eric Zerkel (@EricZerkel) February 22, 2019

I do it to everyone. Its a simple and low key way to say hello. - Tony Casalini (@casalini09) February 22, 2019

Its a learned survival behaviour similar to a smile. It means that the other is not a threat. - max munoz (@maxmunoz94) February 22, 2019

I head nod as a matter of respect for invading their personal space, Silent Supper Mike Collins told us in an email. If I am walking towards someone and we are within 10 feet of each other, I give them a nod. This is like a, Good day. Sorry for being this close to you. I am friendly. We dont need to fight.'

The nod can also take on slightly different meanings depending on the method and context, it seems.

Marcus Helton, a basketball journalist, told Mens Health that he used a head nod during a trip to Asia years back to acknowledge the only four other black guys he encountered during his three-week excursion abroad.

Its a way of acknowledging each others presence and knowing theres backup if some shit goes down, Helton joked in a Twitter direct message.

Derek K. Hubbard, a social media specialist, is from the South; he explained the nod as being part of a kind of Southern hospitality-an acknowledgement of both male and female passersby.

Showing a little kindness to our fellow neighbors can go a long way in helping others feel seen and appreciated, Hubbard told Mens Health in a Twitter message.

While several respondents to our informal survey indicated that a Silent 'Sup can occur among people of any gender, there is a sense that its more of a guy thing.

According to Dr. Lillian Glass, a prominent body language expert, part of the reason for the Silent Sup could be mens tendency to communicate more nonverbally than verbally.

Studies in gender difference research show that women use more words than men to communicate so a head nod is a typically male response towards agreement or approval, Glass told Men's Health in an email.

Thats not to say women cant also Silent Sup, or that women dont nod at all. Its just that they might nod for different reasons, according to Glass. Their nods may not necessarily indicate agreement but may just be a signal to keep talking, Glass said. It is a female gesture of politeness.

For at least some men, the nod appears to be something different-and replete with all sorts of little nuances. Some, for instance, have suggested that an up-nod, which leaves the neck vulnerable, is a move reserved for those you know and trust, while the more protective down-nod is for strangers. Others have posited that its a move guys make in recognition of common interests.

Ben will subtly nod if someone is wearing the same headphones - Kate Bratskeir (@Kbratskeir) February 22, 2019

Omg my dad is a motorcycle guy and all of the motorcycle guys do this weird motionless wave thing - Kevin (@kwprime) February 22, 2019

Im honestly still a little unsure of what to make of the Silent 'Sup-at least as it pertains to its more macho manifestations. If youre nodding at me on the street to prove youre more dominant than me, dont strain your neck-Im not fighting some animal instinct to fight you, I promise.

That said, there is something pleasant about the idea of acknowledging our fellow humans as we go about the business of our day-particularly for those of us who live in cities, where full-on hellos to total strangers can be a little much. I think I agree with Silent Supper J.C. Barraza, who told us in a Twitter message that he [nods] to be nice. Its such a polarized society, Barraza wrote us, and its so easy to be courteous & nice.

A simple nod goes a long way to making someones day slightly better, he said, or less worse.