The #BellyButtonChallenge has taken off in China on Weibo
Indulge us for a second and take your arm, place it round your back and try to reach your belly button with your fingers.
Pretty difficult? Well yes, it does require a little flexibility, but now people are taking it as a signal of fitness, in what is being dubbed the #bellybuttonchallenge.
The challenge, which has no grounding whatsoever in medicine, reportedly began in China on Weibo, the Chinese microblogging site. It has seen thousands post selfies, attempting to touch their bellybutton with the method to show off their "fitness".
The trending topic was mentioned more than 130 million times among Weibo readers and spawned over 100,000 discussion threads.
Some have voiced concern about the trend, saying it is "one more way of scrutinising women's bodies to see whether they are 'good enough'".
Jolene Tan, a senior manager at Aware, a non-governmental women’s rights organisation, told the BBC:
Quirky poses and pictures can be fun but sometimes they also become expressions of competitiveness or insecurity.
We need to do more to promote acceptance of diversity in women's bodies.