A new social media trend has kicked off in China, with thousands of netizens uploading photographs of themselves showing off their bodies and undertaking the challenge.
Popular among many young female users on Weibo, the trending topic - which translates as "reaching your belly button from behind to show your good figure" - was mentioned more than 130m times among Weibo readers.
It also spawned 104,000 active discussion threads, but has also led to concern about whether it's promoting an unhealthy body image.
"Look! Success. More than four hours and I've finally reached my belly button," said Weibo user GayleRabbit.
Another user remarked: "Whoa. Why does my belly button suddenly look and feel brand new?"
While the trend was dominated by many female users on Weibo, a photo uploaded by a male blogger took the microblogging community by storm.
"Is this trend really that difficult? I don't think so," said Weibo user Sough Sa.
His photo showcasing his attempt at touching his belly button, drew 2,634 likes and was shared more than 8,452 times.
It also drew more than 2,000 comments from other users on Weibo.
"You go Buddha! Show the skinny girls how it's done," said one user.
Weibo user MedicalCream Tang Zhao said: "Now you did it! So don't lose weight and please stay the same."
"I always root for the underdog. Now I don't feel so inadequate about not being able to touch my belly button," said another user.
"Does one need to have flexible arms? Or a skinny waist to pull this off?" asked Weibo user Chantilly623.
But some experts argued that China's new belly button trend bordered on promoting eating disorders and "distorting" society's standards of beauty.
"Quirky poses and pictures can be fun but sometimes they also become expressions of competitiveness or insecurity," said Jolene Tan, Programmes and Communications Senior Manager at Aware, a non-governmental organisation in Singapore championing women's rights.
She also told the BBC that the trend seemed to be "one more way of scrutinising women's bodies to see whether they are 'good enough'".
"We need to do more to promote acceptance of diversity in women's bodies."
Can you touch your belly button by reaching behind your back and around your waist?