If your guy does this, he might have a manipulative personality

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They identified four dark personality traits—narcissism, or excessive interest in oneself; psychopathy, or exhibiting an extreme ego and a lack of empathy; sadism, or the tendency to derive sexual pleasure from hurting or humiliating others; and Machiavellianism, or the penchant for exploitation, manipulation, and deception in getting what you want—as possible predictors of sending unwanted images of genitalia.

The goal: to determine "if this a sexually deviant behavior, or is this an advertisement of mate quality."

The findings support what many you might guess: If a guy is unabashedly sending you dick pics you never asked for, there's a solid chance he's a self-absorbed douche bag bent on achieving his own sexual goals, without regard for your own desires.

To put it in very scientific terms. In other words the researchers found a correlation between sending nudes and some toxic traits.

The study authors corralled 240 participants, 72 percent of whom were women, and all of whom had sent an unsolicited nude at some point in their lives. Just over 70 percent of participants identified as heterosexual, about 18 percent as bisexual, 6 percent as homosexual, and the rest as "other."

All of them filled out a questionnaire online, scoring themselves on a Mate Desirability Scale—questions to the tune of, "On a scale of 1 to 7, how desirable as a partner would you say you are, compared to other people?" Then, each person answered different sets of questions designed to gauge their levels of the aforementioned dark personality traits.

Participants were made to rate their answers to two questions—"I think others enjoy receiving pictures of my own genitals" and "I enjoy sending explicit pictures of my own genitals to other people"—on a scale from 1 (strongly disagree) to 5 (strongly agree).

They also had to report ballpark figures for the number of people they'd sent surprise nudes.

Watch men and women spill the honest truth about exactly what they think about cheating:

Men ranked higher than women in each of the deviant personality traits, tended to rate themselves as having more mate value than women did, and charted higher scores on the explicit image scale—which is to say, they tended not only to really enjoy sending people unannounced dick pics, but they also truly believed the recipients liked them.

Regardless of gender, though, people who saw themselves as more valuable mates tended to believe whole-heartily that people truly enjoyed getting their unsolicited nudes, as did the more Machiavellian participants.

Researchers were surprised to see that narcissism, psychopathy, and sadism didn't really predict a person's predilection for sending Snaps of their genitals.

They also speculated that the tendency of Machiavellian types to engage in this behavior with gusto might be indicative of a more "'aggressive' mating strategy, rather than a manifestation of deviant personality traits."

Sending unsolicited nudes, they suggested, "could be a more aggressive tactic for manipulating another individual into a short-term sexual interaction."

The authors are clear that the study's self-reported, exploratory nature means their findings would require more supporting research. Ultimately, though, their conclusions suggest that the aggressive, egotistical dude flexing his dick for the camera believes showcasing his impressive junk will help him bed you faster. Delete his number from your phone. Immediately.