It is a quintessential part of everyday life in China during summertime - men rolling up their shirts and baring their bellies to keep cool.
It is so prevalent there is even an English nickname for it, "Beijing bikinis", although the Chinese capital can hardly lay exclusive claim to the practice.
Now, at least one Chinese city has clamped down on this habit in a bid to curb what it has described as "uncivilised behaviour".
Jinan, the capital of Shandong province in eastern China, has issued a notice banning men from exposing their bellies in public, even as temperatures soared to a high of 38 deg C last Tuesday and the hot spell looks unlikely to be over soon.
In the name of maintaining the city's image, officials are also going after those who commit any of a long list of transgressions, including taking off one's shoes in public to air the feet, spitting, littering, quarrelling or shouting in public, queue-cutting, lighting up in non-smoking areas, lying down on public benches and hanging their clothes in public places.
The notice also urges government departments, the media and grassroots organisations to do their part to expose such "uncivilised behaviour" and keep it in check.
Party cadres and government officials should especially "demonstrate by example", the notice says.
Baring body parts seems to be particularly objectionable; the coastal city of Tianjin outlawed toplessness in March. The act attracts a fine of up to 200 yuan (S$40), as does cutting queue or grabbing seats on buses and trains.
China has for years been trying to make its people kick bad habits that have made the news from time to time.
Tourists from China have sullied the country's image by urinating in public, destroying ancient relics and leaving rubbish behind - enough for the country's tourism administration to issue a 64-page Guidebook For Civilised Tourism in 2013, and a public blacklist in 2016 of those who behaved badly.
Within the country, local governments have launched various campaigns. Last year, the city of Suqian in Jiangsu province handed out an updated set of etiquette guidelines that included: Don't wear pyjamas in public, and let others out of elevators before you get in.
Beijing and Shanghai also launched major offensives to promote civility in the run-up to the 2008 Olympics and 2010 World Expo, respectively, such as getting people to queue up, not to spit, and refrain from pushing and shoving.
Social media reactions to the banned belly-exposure have been mixed, ranging from ridicule to calls to roll it out nationwide.
"This is really not gracious behaviour in public, forcing you to look at them," said one netizen on blogging site Weibo.
Another said: "Meddling so much. People outside of China expose even more."