A motorcyclist turns from Sims Way into Geylang Lorong 6, and holds up two fingers before stopping in front of a roadside coffee shop next to the junction.
A man who has been standing by the road, hands him two packets of cigarettes in exchange for what appears to be $10. The motorcyclist then speeds off - the entire transaction taking a matter of seconds.
In the next hour alone, at least 30 motorists take part in similar transactions.
Acting on a tip-off, about 30 Singapore Customs and auxiliary police officers raided the vicinity on Friday evening, arresting three suspected peddlers, all Singaporean men.
Three cartons and 40 packets of contraband cigarettes of assorted brands were seized. The street value of the cigarettes was about $730, while the duty and tax evaded was about $610.
Mr Lim Guan Cheong, head of suppression and community engagement at Singapore Customs, said that such enforcement operations are conducted "regularly" in Geylang. Last year, 333 buyers and 159 peddlers were caught in Geylang alone.
Before the latest arrests, The Sunday Times, after receiving a tip-off from a reader, spent two hours last week observing the illegal operation.
About two or three men, who appeared to be in their 40s and 50s, seemed to be peddling cigarettes along the road to passing motorists.
Every time a customer approached, the men would retrieve the cigarette packets from a rubbish bin beside the Kah Ho Eating House coffee shop.
In a span of two hours, spread over two separate days, The Sunday Times counted at least 70 of these transactions taking place.
Most customers seemed to buy two packets, although one was seen buying as many as six. A few buyers also received a plastic bag wrapped around what looked like a carton.
Mostly young and middle-aged men, they would usually swing by in motorcycles but some drove cars, lorries, trucks and taxis, and some were on bicycles. There was the occasional buyer who came on foot. All of them seemed to be familiar with the location and how to buy the cigarettes.
About six or seven other men and women sat around the coffee shop or across the road, seemingly acting as lookouts. They would occasionally exchange money with the peddlers.
Sales usually paused at around 6pm, but another group of men on the opposite side of the road, off the driveway of an apartment building, appeared to take over sales.
A total of 2.9 million packets of contraband cigarettes were seized last year - almost double the 1.5 million packets confiscated in 2012, and up from 1.9 million in 2011.
The number of smokers caught buying contraband cigarettes also increased - 6,400 buyers were caught last year, compared with 5,977 in 2011.
Members of the Tobacco Association of Singapore (TAS) said in an earlier interview that while enforcement action usually focuses on syndicates, smaller-scale raids are still helpful.
"Street-level enforcement is also important," said Mr Ann Hee Kyet, manager of corporate affairs for tobacco company Philip Morris Singapore. "There is a deterrent effect."
The TAS plans to step up its monitoring of the illicit market by conducting two annual surveys of smokers from this year instead of one.
Singapore Customs similarly plans to do more research to better estimate the supply of contraband cigarettes here.