What links milk powder, Apple gadgets, lobsters and Louis Vuitton bags? Border smuggling, of course.
Every day, thousands of mainlanders travel across the border to buy coveted products to sell back home for profit. Hong Kong boasts cheaper prices, the latest technology (the iPhone 5 is as yet unavailable on the mainland), and better food safety standards than its bigger neighbour. Meanwhile, Shenzhen residents can enter the special administrative region numerous times a day on multiple-entry visas, making logistics easy for enterprising traders.
Hongkongers, however, are not impressed. Smuggling has led to rising prices, packed trains heading north and empty shelves in supermarkets.
"Seize our milk powder, seize our hospital beds, seize our buildings, seize Hong Kong social welfare - they have already seized everything," said one comment posted on the blog Dictionary of Politically Incorrect Hong Kong Cantonese. It also reported that smugglers had hoarded stocks of the milk drink Yakult after claims emerged on the mainland that the product could enlarge female breasts.
On the mainland, though, these exasperations are seen as unfair and unfounded. For years, Hong Kong residents and tourists have nipped over the border to buy cheap goods, from knock-off designer bags and fake DVDs to custom-made suits.
True, some items - namely luxury goods, which are saddled on the mainland with a burdensome tax - are hardly essentials. But fear of contaminated food in a country where scandals have ranged from melamine-tainted milk to glow-in-the-dark pork is very real, and will fuel demand for so-called safer brands from Hong Kong.
Authorities have started to crack down on smugglers (last month, in Guangdong province alone, 160 were arrested and at least eight have been jailed so far). But instead of blaming the buyers and sellers, some believe the system must be changed.
"Improving the quality of domestic goods and enhancing food safety is the only way," says Sina Weibo user Daicimoli.
Han Chongming, 25, an automotive engineer from Jiangsu province, agrees.
"[Ordinary mainlanders] worry about illegal cooking oil, poisonous milk, high living costs, low salaries, rocketing housing prices … Don't blame the common people," Han tells Post Magazine. "Instead, blame the system for forcing them to do this."