The creepy office guy approaches you in the break room and you're immediately uncomfortable. What is it about him? The greasy hair? The weird laugh? The painfully awkward chit chat?

All of the above, says a new study. Though we've been identifying other people as "creepy" for generations, few definitions of what creepy actually is existed. But now, a study outlines the traits and behaviors that give some guys — yep, men score higher than women when it comes to ickiness — that creepy quality.

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“Creepiness is all about not being able to figure out whether there is a threat,” said Frank McAndrew, Cornelia H. Dudley Professor of Psychology at Knox College and author of the study. Men may be seen as creepier than women because they're perceived as more menacing, according to McAndrew.

To research the topic, McAndrew asked 1,341 people to complete an online survey. The participants ranked how creepy 44 behaviors or traits were on a scale from one to five, where one was very unlikely and five was very likely. They were also asked which occupations and hobbies were the creepiest.

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What's "creepy"?

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Creepy traits and behaviors include:

Standing too close to someone

Smiling peculiarly

Talking too much about a topic, especially sex

Laughing at inappropriate times

Not letting someone out of conversation

Displaying unwanted sexual interest

Asking to take pictures of people

Displaying too much or too little emotion

Having bulging eyes

Having long fingers

Having pasty skin

Having greasy hair

Having dark eye bags

Wearing dirty or weird clothes

Licking lips

Creepy hobbies include:

Taxidermy

Collecting things, including dolls, insects, and — eww! — fingernails?

Any kind of watching, such as bird watching or photography

The creepiest professions will probably surprise no one:

Clown

Taxidermist

Sex shop owner

Funeral director

Taxi driver

The participants answers indicate that it's possible creepy people simply don’t understand social cues and norms. Wearing dirty clothes or laughing inappropriately, for example, fall outside what people expect and signal a warning about someone.

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“The survey points out just how negatively we react to people who do not follow unspoken rules for social behavior,” said Pontus Leander, an assistant professor of psychology at the University of Groningen, who studied how creepy people literally give us chills.

“I was also struck by the finding that most indicators of ‘creepiness’ have to do with nonverbal or physical characteristics. Creepiness appears to have a physical dimension,” said Leander.

More research needed

But at least one expert doesn't agree with the paper's findings.

“It’s all correlational so causal inference must be muted, e.g., that ‘creepiness’ is due to the ambiguity of threat, goes too far,” said Frank Farley, a professor of psychology at Temple University.

“Further research needs to explore ethnic, cultural, diversity, social class, literacy, personality and other differences in judgments about creepiness.”

This story was originally published in April 2016.