It began with a minor episode. A couple from China allowed their child to relieve herself on a busy Hong Kong street.
Two Hong Kong men took exception to it and started arguing with the couple. The clip of their heated exchange caused a stir online last week.
The Hong Kong media praised the two men as heroes who had fought against ill-mannered mainland tourists.
Now the mainlanders are hitting back.
They have launched an online campaign to urge mainland Chinese parents to take their children to Hong Kong next week and let them urinate in the streets to familiarise locals with "natural functions", Hong Kong daily South China Morning Post reported.
The idea came as state media weighed in on the row, saying that both the parents and those who objected needed to "raise their level of civilisation".
User Haijiao No 68 wrote on popular mainland forum Tianya ahead of the May 1 public holiday: "Take children to Hong Kong and let them urinate in Hong Kong's streets.
"Let's see who will come and take photos. They will see it as natural after they have been familiarised with the act.
"Mainlanders are the dads and mums of Hong Kong people. Without us, can Hong Kong live carefree?"
The video images have drawn more than a million comments and reposts on Weibo alone.
It reignited the debate on social media platforms over the behaviour of mainland tourists in Hong Kong.
In a commentary published in its overseas edition, China's People's Daily questioned whether the duo who filmed the child's act had acted properly, while calling for a need for "mutual civilisation and understanding" between tourists and Hong Kong people.
It said that with 30 million mainlanders visiting Hong Kong last year, it was inevitable that some "would not act up to modern standards".
"It is an act of civilisation to understand others' difficulties," it read. "No one occupies the moral high ground of civilisation."
The editorial followed an opinion piece in another China daily, the Global Times, which said the couple who took the pictures were "more uncivilised" than the family allowing the child to urinate by the roadside.
In the video, the mother is seen telling the crowd of onlookers: "The child was going to pee in her pants, what do you want me to do?" before a scuffle broke out.
The parents then try to snatch the memory card from the young man's camera.
The husband and wife were arrested on suspicion of theft and assault following the incident.
She was bailed while he was released unconditionally.
Hong Kong laws prohibit those in charge of a child under 12 from permitting the child, without reasonable excuse, "to obey the call of nature in any public street". Violators face a HK$2,000 (S$325) fine.
This article was published on April 27 in The New Paper.
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