Posing as a woman, full-time national serviceman Ramlan Abu advertised sexual services online and used his victims' naked photographs to extort a total of $6,000 from them.
Yesterday, Ramlan, 24, pleaded guilty to 14 charges of extortion, cheating and drug possession.
He was sentenced to 6½ years' jail and 10 strokes of the cane, with effect from Oct 25 last year, when he was remanded.
Fifty other similar charges were taken into consideration.
The court heard yesterday that Ramlan had a profile on online classifieds website Locanto, where he advertised sexual services under female names such as "Ellisha" or "Mariaa".
Those interested in procuring his services would send him a text message or call him on his mobile phone number, thinking that they were contacting a woman.
Between March and October last year, he used the naked photos sent to him willingly by at least five victims to extort money from them. He did this on several occasions.
The victims cannot be named because of a gag order.
In one of the cases, a 22-year-old Singaporean man saw Ramlan's advertisement online and contacted him through WhatsApp on Sept 24 last year. During the conversation, the man sent Ramlan a naked photo of himself, and later, on Ramlan's suggestion, the pair did a video call.
Deputy Public Prosecutor Zhou Yihong said: "At the start of the video call, the victim still thought he was calling a female, as the accused looked like a woman on video."
The victim then agreed to pay Ramlan $55.55 to see the latter perform a sexual act.
While the pair were doing so, the victim realised Ramlan was actually a man, said DPP Zhou.
Later that day, Ramlan sent the victim a Facebook post with photos showing the victim's genitals and face, and said that if the victim did not transfer $90 to him, he would not take down the Facebook post.
Fearing that the post could harm his reputation, the victim acceded to the request.
Ramlan used the same tactic to extort a total of $3,110 from the man on 31 occasions between Sept 24 and Oct 22 last year, when the victim finally made a police report.
The next day, Ramlan was arrested. During a police search, a packet of methamphetamine, or Ice, and an improvised plastic ware meant for the consumption of the drug were found in his possession.
Yesterday, DPP Zhou said Ramlan's extortion offences were committed over an extended period, and "almost on a daily basis" in September and October last year.
Calling the case "quite unprecedented", she urged the court to send a firm deterrent message with a harsh sentence.