"On the balcony, I felt eyes on me. I heard people around me — cars and talking. Everyone could see us, whether they wanted to or not. The whole world could watch."

World, meet Allie. Allie is a friend of mine with a particular proclivity towards public sex, and right now, she's in the middle of describing what it feels like to have it on the 6th floor balcony of her Los Angeles apartment building.

The balcony faces Sunset Boulevard.

Perhaps you've heard of it.

And since you asked, it was standing up, from behind. So people could get the full picture.

"I wanted to be seen," she tells me. "I wanted to be part of the story someone told their coworkers about their weird walk to work."

Allie wouldn't go so far as to call herself an exhibitionist — she doesn't need to self-expose for gratification — but she does enjoy thrill of public sex when it happens.

When I ask her why, she gives me two reasons.

First, she likes the control. "I like that I have some distant, untouchable control over other people's arousal … or even disgust," she says. "It makes me feel powerful. Regardless of what people think when they see it, they'll have a reaction to me, and some part of that turns me on."

Second, it makes her feel desirable. Being so flagrantly fucked within the optical field of hundreds of people sends a jet-engine-loud message that she is fuckable. Moreover, according to our societal standards of fuckability, that she is worthy.

Ah. There it is. Worthiness. Sex in public scratches the urgent itch of self-confidence most of us have; the fickle part of our egos that craves visible validation. We want others to know we're worthy. In this case, public validation means that the risk of public sex is worth the reward of getting caught.

That feeling of worthiness also comes from the tangible sense of sexual urgency public sex brings — it's almost as if the people involved are so inimitably deserving of sex (and therefore reproduction) that they can't possibly wait to show it decently, in private.

On a very deep, evolutionary level, this brings out something important inside us; something that says our fuckability is related to our capacity for survival. And isn't that what confidence really is? Faith in our own abilities to not die?

Miko Technogeisha, a blogger for YourTango, confirmed the relationship between sexual expression and self-worth in a 2014 article in which she describes how publicly exploring her kinks helped increase her confidence. While public sex wasn't something she specifically mentioned, she did talk about the therapeutic phenomenon of being seen — simply putting herself on display as someone with particular kinks reversed the decades of insecurities she'd accumulated about her body and sexual performance.

"I know I should be able to love myself and be self-accepting," she wrote, "but I don’t seem to be able to fill my self-esteem bucket on my own. It probably sounds shallow and vain that an unsolicited compliment from someone make me feel so good, but it does … In a culture that worries about compliments seeming creepy, obtrusive or sexist, we don’t get many compliments as everyday, average adults."

What's the ultimate compliment? Being so irresistible that someone has to fuck you right here, right now, in front of all these people.

So much of our self-confidence has to do with how we perceive other people see us. But, imagine if you could work it so other people saw you in a way that's objectively desireable and therefore worthy of survival — that's what public sex does for people.

Recent research on public sex confirms this.

A new study, published in The Journal of Sex Research, surveyed men and women between the ages of 17-35 to try to uncover the motivations and outcomes of public sex, and they found the main reason people do it no more complicated than just to show off. More floridly, the researchers found that people who loved hooking up publicly did so "to enhance their image or status by proving they were capable."

Mel, a 29-year-old ex-pat hailing from Australia is Allie's best friend. He's also attracted to sex in public because of what it does for his confidence, something he says has a lot to do with his frequenting of the infamous San Francisco sex club Power Exchange. There, he tells me they've got a large, black bed where guests can publicly perform their sexuality for others. Often, he winds up on that bed, encircled by a crowd of spectators. Some get off at the sight of him and his partner; some appear more interested from an entertainment standpoint — as if they were watching TV.

Regardless of what they're there for though, Mel finds this exhilarating.

"Having other people watch me with someone kind of makes me the star of the show," he says. "All the attention makes me feel worthy of the attention, if that makes sense."

Sure does. However, self-worth isn't the only reason someone would want to be overtly ravaged.

Other reasons the survey participants listed for aggravated PDA included demonstrating their relationships to others, fun and games and simply trying to hook up with someone who just happened to in public view at the time.

Motivations for these reasons were divided on gender lines. Thirty-eight percent of male respondents wanted to gain respect from their peers, while 27 percent of women said yes, they wanted cred, but they also wanted to make other jealous. One respondent said she wanted "girls to be jealous, and me to feel better about myself." Another told researchers she hoped making out with someone in front of her ex-boyfriend would make her seem more desirable to him.

All of these reasons — respect, feeling better about oneself, inciting jealousy — go back to self-worth.

Even the most unexpected reason for loving public sex that I encountered does — a friend of mine named Danielle told me she loves public sex because she's got an inherent submissive streak to her. Being naked and engaging in sexual activity in the view of others makes her feel vulnerable, and even a little humiliated, something that actually turns her on.

"There's just something about the taboo and the wrongness of what I'm doing that thrills me every time," she tells me. "I like feeling unashamed about something so many people would feel ashamed about. I also love that me at my most vulnerable could be pleasing to more than just one person."

That same attraction to vulnerability and humiliation is actually what sparked her interest in BDSM, something that's lead to her current moonlight career as a professional sub in a dungeon in L.A.

Interestingly, it's not uncommon for people like Danielle, who love sex in public, to also be more erotically inclined in other areas — exhibitionists (as well as less-fetishistic fans of public sex) also tend to be more sexually expressive and adventurous than people from both kinky and vanilla walks of life. In fact, Psychology Today reports that, "Compared with the population as a whole, exhibitionists are more sexually active. They are more easily aroused, masturbate more often, and have partner sex more frequently. They’re more sexual in general, so they’re apparently more interested in exploring the fringes of sexual expression."

And just how many people are into this kind of thing?

Statistics on public sex vary so drastically that it's almost funny. An old ABC news study from 2004 found that 57 percent of American adults have had sex in a public place, while a more recent Swedish study vivisected that number to 3.1 percent, with every possible estimate in between.

Yet, while it's unclear exactly how many people are fucking in plain sight these days, what is clear is what the penalties are for doing so.

In most states, sex in public is considered either a lewd act (where no genitalia are exposed), or indecent exposure (visible boobs, dick or vagina). Both are misdemeanor crimes punishable by a hefty or jail time, and in some states, being charged with either requires registration as a sex offender as well.

Of course, for people like Allie, Mel or Danielle, that risk is worth the reward. It's easy to extrapolate why — getting away with something risky is a form of survival. And to reiterate: survival is self-worth. That's what makes it so empowering.

"I'm not afraid of getting caught," Allie tells me. "I don't know who would take the time out of their day to report me. I'm not doing it directly in front of someone's face … I'm not getting fucked at them. It's more like I'm doing my thing and if they happen to notice and watch long enough to get pissed, then that's their problem."

"Plus," she says, "that's what makes it hot. It's not so in-your-face and personally offensive that it would actually ruin someone's day, yet it's taboo and visible enough to get me off."

Well, one thing's for sure. I'll be checking out a lot more balconies lately.