First it was pieces of A4 paper to obscure their tiny waists, now Chinese women are using their iPhones to highlight the slenderness of their knees.
The "iPhone 6 legs" trend on the Chinese social media site Weibo shows hundreds of photos of women using their mobile phone to cover their knees.
These so-called "beauty tests" have been widely criticised, with many saying they promote unhealthy body images.
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"These everyday trends bore me," the website What's on Weibo quotes one user as saying. "Your standard of beauty is not healthy."
Similar "challenges" that have gone viral on Chinese social media include women competing to hold the most coins on their collarbone as well as attempting to reach around their waist to touch their belly button with the back of their hand.
The effect on their social media behaviour is noticeable, says iRead, a popular media source on Weibo. "One no longer has the courage to post to their friends if one does not have the right body lines," it says.
"It is unclear whether the challenge calls for an iPhone 6 or the bigger iPhone 6 Plus," says Alicia Tan on Mashable. "However, the growing popularity of yet another beauty meme is concerning for the unhealthy body image it encourages in women."
Tan also suggests the arrival of the even smaller iPhone SE could spark more worrying "beauty tests" in the future.
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