I knew there were people who crossed the border regularly from Shenzhen to buy up goods from Hong Kong for their own use.
And then there was the iPad and iPhone frenzy when people picked up several at a time to bring back to the mainland to sell because they were cheaper in Hong Kong and not yet available in China.
But I didn't realize there were people who cross the border several times a day to ferry goods to China.
The media calls them mainland parallel importers but they're more like drug mules except they're not carrying illicit drugs.
They come into the city armed with a shopping list and buy things from milk powder to cosmetics, bring them back and then they are resold to mainland customers. Then they do it again, four to five times a day, everyday.
One woman told one media outlet she helped a Shenzhen seller one day a week for the past year. She made three trips a day, making 100 RMB ($15.75) per trip. Basically a low-paid mule, right?
And now Hong Kong may get many more of these mules particularly around the Sheung Shui area because the Shenzhen government is relaxing travel permit rules from next month, thus allowing 4.1 million non-permanent residents to come to Hong Kong on multiple-visit permits.
Shopkeepers are probably rubbing their hands with glee at the prospect of even more customers, while the rest of us are going to have to deal with higher rents, more expensive goods and more social problems resulting from even greater cross-border traffic.
People coming to Hong Kong to visit relatives, shop and go sightseeing is fine, but those deliberately coming here to buy up our goods and then reselling them for even a small profit is not acceptable.
As a border patrol officer, wouldn't you be raising eyebrows if someone crossed the border more than twice in one day, everyday?
Tourism Board Chairman James Tien Pei-chun has already spoken out against the relaxing of the permit rules, claiming most of the people coming in are these parallel traders.
"They are not tourists. They are illegal workers," he said in a radio interview. He said these visitors who don't have a hukou in Shenzhen would have less purchasing power and would stock up on things like baby formula instead of visiting the city's theme parks.
While Tien may be making these statements ahead of the September 9 election, he is reflecting the views of the general public.
It'll be interesting to see how receptive Hong Kong people are to his comments. There are concerns Chief Executive Leung Chun-ying did not do enough to talk to the Shenzhen authorities about their decision and how it would impact our city... or was he complicit?
In any event more mainlanders in the city is going to result in more social tensions for sure.