Psychologists explain science behind getting the 'ick' - why are our brains programmed to be cringed out by things opposite sex do?

There may be an evolutionary reason you become instantly unattracted to your crush when you discover they are a loud chewer.

'The ick' is a term made popular on TikTok and Instagram to describe that feeling when attraction turns into a sudden, cringing disgust toward another person, often in a budding romance.

Common examples of ick triggers are bad hygiene, arrogance, and rudeness - but many have reported seemingly innocuous things like walking with a wide gait, sleeping on navy blue sheets, or even abbreviating breakfast to 'brekkie.'

Now, clinical psychologists have told DailyMail.com they think one of two things is going on: It could be a primitive gut warning to steer clear of danger - or it could be you sabotaging a relationship due to your own relationship issues and attachment style.

Do dirty fingernails give you 'the ick'? According to psychologists, the ick is a feeling of disgust, a primitive emotion meant to keep us safe.

Do you get the ick if you go to a potential romantic partner's house and see their garbage is overflowing? In this case and others, the ick may be your body trying to warn you about potential illness. But even though that gut feeling can be powerful, it doesn't have to be a dealbreaker, psychologists say.

READ MORE: Women confess the gross, funny, and outrageous things men do that give them 'the ick'

'When he wears a t-shirt and nothing else.'

According to Dr Carla Marie Manly, the evolutionary theory says the ick may be part of a primitive instinct meant to protect us against things that could hurt us. For example, our sense of disgust at unpleasant tastes, smells, and textures steers us away from eating poisonous mushrooms or spoiled food.

'The ick factor is the result of a sensation in the gut of disgust,' Manly, a clinical psychologist, told DailyMail.com.

With people it's a bit more complicated, though.

In the modern era, the ick may warn you about different dangers than our ancient ancestors dealt with, when their sense of disgust told them to sleep far from the part of their cave where they defecated.

The ick has more to do with other people, and whether they will be suitable partners.

'Something in that person or in their mannerisms, creates a sense of disgust,' said Manly.

A date yelling at a waiter or criticizing the way you talk may be a sign that they could be abusive in the future, or a bad parent to your child.

They could even remind you of similar, painful memories from your own childhood.

But Dr Leslie Feil, also a clinical psychologist, said the ick tends to be more common in people with insecurities of their own, especially people with an avoidant attachment style.

Do you get the ick when you see a man drink from a straw? Maybe you're looking for a reason to reject him as a potential partner.

Greeting card seller Thortful surveyed 2,000 UK men and women on their icks, and the top contenders were bad hygiene. arrogance, and noisy eating.

Men and women agreed on the top three icks, as well as bad breath as number four. Spitting on the street, being rude to hospitality staff, and crude jokes also topped the list.

Imagine you're on a first date with a man and he drinks from a straw, or you're on a first date with a woman and she turns out to be a picky eater.

Do you get the ick?

Feil said people sometimes feel the ick when reality shatters fantasy. And these fantasies are often encouraged by romantic movies, or listicles about qualities to look for in a partner.

'That's the phenomenon that I see the most, is that people have an idea of this idealized partner,' she told DailyMail.com.

If you do find you get the ick over and over again with different people, therapy or other tools for self-examination could help you discover why you are so quick to disqualify a suitor, she said.

Someone who exhibits this style of relating to others may have an avoidant attachment style, which they confuse with the ick.

'They have difficulty forming relationships with other people, they may suddenly become feel repulsed, because they're afraid of getting to the next step with the other person,' she said.

Our attachment style develops in childhood, and it colors how we approach relationships for the rest of our lives.

If a man putting on lip balm gives you the ick, you may have other unrealistic expectations for a potential romantic partner.

Some women report getting the ick when a man won't eat vegetables. In this case, they could be responding to a sign that he is not healthy or mature. But this kind of quirk doesn't make them unlovable, and it doesn't need to be a dealbreaker, psychologists say.

An avoidant attachment style can come from parents or caregivers neglecting to show care or possibly failing to provide basic needs like food and shelter.

In adulthood, people with an avoidant attachment style may feel overly self-sufficient, like they don't need anyone else - especially since they may view other people as unreliable and untrustworthy, based on their upbringing.

This fear of intimacy, then, can show up as the ick.

'And we often work through that in therapy, to understand it better, to go about it in a safer way,' said Feil.

Sometimes, if we get the ick over a new partner, the feeling of disgust will go away over time as we become acclimated to their quirks - if they clap when the plane lands, or they don't put a coaster under their glass, for example.

Whatever their specific quirks, the other person may not check enough boxes on the list, but that doesn’t have to be a dealbreaker, said Feil.

'I think those little pet peeves or little annoyances that we all have with other people fade a lot when we feel compassion towards the person that we're interested in, and it's not going to be something on a checklist most likely.'

Instead of looking for red flags, then, perhaps you can look for qualities you like in another person.

Manly tends to agree.

'We are all imperfect,’ she said. ‘We are all going to have quirks. And if somebody is doing something that is not harmful to you, maybe it is a growth opportunity for your ability to be more tolerant, for your ability to accept imperfections.'