A butt-naked humanoid creep is the internet’s worst new viral star. The main character in a video known only as “Hi Stranger” has been described as “the creepiest thing ever,” “exceptionally weird,” and “bizarre”. But mostly they just called it “creepy.” While the internet’s reaction has been fairly consistent, what’s not clear is what, exactly, makes this dewy-skinned sweet talker so creepy. And according to one psychological theory, that vagueness is exactly what creeps us out.

First, a bit about our slippery friend: Hi Stranger lies bare-assed, flat on its stomach on what appears to be a smear of mayonnaise. Its skin is only slightly less pale and is similarly glossy. In its perfectly round head are two widely spaced, black-rimmed eyes, and a black curved mouth — nothing else. When it opens, the mouth issues a soft, slightly nasal male voice that caresses the viewer with compliments. Sometimes, its eyes grow heavy-lidded. Those bedroom eyes rarely stop making contact with yours. Together, these characteristics make a forcefully creepy impression.

Perhaps it’s not surprising that they’re the same characteristics that were listed in a 2016 article in New Ideas In Psychology titled “On the Nature of Creepiness.”

In their attempt to determine what creepiness really entailed, the scientists behind the study asked their 1,341 international participants to rate the likelihood that a “creepy person” would display any of 44 different behaviors. Many of the traits that made the cut are the same ones that characterize Hi Stranger: a “peculiar” smile, bulging eyes, pale skin, excessive thinness, and displaying too much (or too little) emotion. Also included on this list were certain actions, like repeatedly steering the conversation to a single topic (especially sex), or asking to take a picture of you (“I want to remember all of your shapes,” Hi Stranger says, sketching you on a piece of paper as he gazes into your eyes).

While these traits may seem mostly benign taken on their own, the authors of the paper hypothesize that, together, they create the feeling of being “creeped out” because they add up to create a sense of ambiguity.

“It is our belief that creepiness is anxiety aroused by the ambiguity of whether there is something to fear or not and/or by the ambiguity of the precise nature of the threat (e.g. sexual, physical violence, contamination, etc) that might be present,” the researchers write in the paper.

The “paralysis” we feel after encountering things that create a sense of ambiguity is what we define as “creepiness,” they explain. We probably wouldn’t feel conflicted about how to feel if Hi Stranger was a real-life, naked person making very obvious sexual passes at us because the appropriate response would be clear: Get the fuck away! But, no — Hi Stranger’s not-quite-human appearance lies firmly in the uncanny valley, its ceaseless eye contact is at once loving and discomforting, and its voice says sweet things but is so low and close it feels as though it’s intruding on our personal space. According to the ambiguity theory, we can’t tear our eyes away because we don’t know what to do.

What gives additional credence to the ambiguity theory is the fact that Hi Stranger’s manner is so vague that some people actually think it’s soothing rather than creepy; in some cases, he’s a little bit of both.

It’s slippery, that’s for sure. And while it’s not clear whether it’ll leave you with chills and a vague sense of having been violated or a feeling of warmth and acceptance, what’s certain is that nobody, after watching it, is quite sure how to articulate what just happened. And that may be why we can’t help but watch it again.