Women, and even some men, are stepping into cyberspace to show the world they can reach their arm around their back to touch their tummy. If you have not heard of it, they are doing the belly button challenge, which went viral on social media last month.
Some quickly moved on to the collarbone challenge where they got busy stacking coins in the groove of their collarbone. All this, just to show how skinny they are.
The latest online skinny fads come on the heels of last year's viral social media trends. There was the "bikini bridge", which is the space between a woman's hip bones that showed how flat her tummy is; and the "thigh gap" that apparently proves one has ultra-slim legs.
Such challenges can be unhealthy for the public, not to mention those who have a negative body image.
"Such social media activities promote poor body image and affect self-confidence," said Dr Lee Ee Lian, a senior consultant psychiatrist at Promises, a mental health clinic at Novena Medical Centre.
The danger lies, said Dr Lee, in the risk of triggering eating disorders, depression and other psychiatric disorders in some people.
"Suicides have been known to be precipitated by social media activity, particularly when a person falls into a depression and already has suicidal thoughts," she pointed out.
"Cyber bullying over social media, including body image postings, can cause suicides too."
Dr Ng Kah Wee, a consultant at Singapore General Hospital's psychiatry department, said the public's view of an ideal body is influenced a lot by the media, including advertisements on weight loss, slimming treatments and food fads.
"Such trends towards thinness can be so prevalent that it could be perceived as normal behaviour," she said, adding that this further perpetuates abnormal eating behaviours.
Dr Christina Low, a general practitioner at SMG Medical, a Singapore Medical Group clinic, said the skinny trends and challenges on social media "increase body dissatisfaction... and, they are not an effective way to gauge weight control".
A higher baseline body image dissatisfaction among female college students in Australia was linked to the use of Facebook, according to a study in this month's Journal Of Eating Disorders. It was also linked to a higher risk of eating disorders.
These findings are similar to that from a study in China last year, which showed that women who are heavier Internet users are more likely to have misperceptions about their body and to worry more about their eating, said Dr Lee.
Those with a negative body image risk developing eating disorders - complex mental illnesses that arise out of a person's severely low self-esteem and negative view of the way their body looks.
Symptoms may begin insidiously, with the person initially wanting to lose weight, exercise more and keep to healthier diet, Dr Ng said.
"However, when one is preoccupied with losing weight, keeps to an extremely restrictive diet and a rigid exercise regime and even resorts to measures like vomiting, the situation may have taken a turn for the worse," she said.
One can remain ill for prolonged periods of time, or develop other psychiatric conditions, such as depression, warned Dr Ng.
Other long-term physical effects of being severely underweight and malnourished include amenorrhea (disruption of menstrual cycles), infertility, stunting of growth, osteoporosis and impaired cognitive and mental functions, she said.
"Having a positive attitude towards body image is paramount," said Dr Ng.