Sun’s out, buns out.

A controversial new wellness practice that encourages tanning one of the body’s more delicate areas has made its way to Hollywood — to seemingly disastrous effects.

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Actor Josh Brolin tried out the "perineum sunning" craze, which touts the alleged benefits of tanning the thin area of skin between the anus and the vagina or penis. The practice has recently gained steam after a video posted by holistic influencer Ra of Earth suggested such "sunning," claiming that it provides one with “more energy from” the sun in 30 seconds “than you would in an entire day being outside with your clothes on.”

Another influencer, who goes by MetaphysicalMeagan, also made headlines for her similar claims of "perineum sunning" for the benefit of health or energy.

Thousands of people on social media have liked and shared the “bum sunning” tactic – with many touting that it gives them more of an energy boost than caffeine. And a few mocking the practice. 

Thousands of people on social media have liked and shared the “bum sunning” tactic – with many touting that it gives them more of an energy boost than caffeine. And a few mocking the practice.  (iStock)

However, what Ra of Earth apparently failed to mention was to not overdo it with vitamin D — a lesson Brolin learned the hard way.

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“Tried this perineum sunning that I’ve been hearing about and my suggestion is DO NOT do it as long as I did. My pucker hole is crazy burned and I was going to spend the day shopping with my family and instead I’m icing and using aloe and burn creams because of the severity of the pain,” Brolin shared on Instagram, along with a string of curse words calling out the “stupid” trend that may in fact be detrimental to one’s health.

Actor Josh Brolin attends a news conference for the film

“Tried this perineum sunning that I’ve been hearing about and my suggestion is DO NOT do it as long as I did," the actor advised others on Instagram. (Reuters)

Thousands of people on social media have liked and shared the “bum sunning” tactic – with many touting that it gives them more energy. A few, of course, are also mocking the practice.

Aside from Brolin, Shailene Woodley was an early adoptee of sunning one’s nether regions. In a 2014 interview with Into the Gloss, Woodley shared that she sunbathes her vagina to recharge.

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"I was reading an article written by an herbalist about yeast infections and other genital issues, and she said there's nothing better than vitamin D."

She went on: "If you're feeling depleted, go in the sun for an hour and see how much energy you get. Or, if you live in a place that has heavy winters, when the sun finally comes out, spread your legs and get some sunshine."

However, the Hollywood elite may be disappointed to learn that the practice of sunning below the belt is hotly discouraged by doctors, as the skin down there is more likely to burn and develop melanoma, even with SPF, Health.com reports.

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“As a dermatologist, I cannot recommend any sun exposure without sun protection,” Dr. Nazanin Saedi, director of the Jefferson Laser Surgery and Cosmetic Dermatology Center, told Health.com. “These areas, just like other areas of the body, do need sun protection and clothing tends to provide that.”

Instead, doctors advise getting enough vitamin D through diet — instead of sun-worshipping.