She sought him out for sex after coming across his profile during a holiday in Hong Kong in 2013.
They had a sexual encounter the first time they met and carried on with each other for two years.
The woman from Singapore would pay for the gigolo's expenses when she visited Hong Kong or when they went on holidays. She gave him money as "rental fee" as she knew he had financial troubles.
But things soured in July when the 67-year-old Singaporean woman tried to end the dalliance with the 41-year-old, who demanded $100,000 and threatened to disseminate a nude picture and humiliating video clips he had taken of her without her knowledge.
She bargained the sum down to $60,000 and he came to Singapore on Sept 3 to collect the money - only to be arrested at the airport.
His mobile phone - which had the picture and two video clips of her engaging in sexual activities with him - was also seized.
Yesterday, freelance masseur Calvin Mok Wai Lun was jailed for 13 weeks after he pleaded guilty to an offence under the Protection from Harassment Act.
It is the first transnational crime under this Act, whereby the crime was committed outside Singapore and the victim was in Singapore.
Deputy Public Prosecutor Sheryl Janet George said Mok and the victim developed a relationship after meeting in 2013, and often communicated using the WhatsApp messaging service.
When the victim sought to break up their relationship, Mok sent her nude photo to her on WhatsApp and threatened to send that picture and video clips of her to a man she knew.
He also sent voice clips threatening to ruin her career and destroy her reputation unless she paid him $100,000.
Distressed, the victim lodged a police report on Aug 26.
DPP George highlighted aggravating factors such as Mok's attempt to extort $100,000, and how relentless he was in threatening to disseminate the photo and video clips.
Mok's assigned lawyer from the Criminal Legal Aid Scheme, Mr Troy Yeo, said Mok committed the offence as he was desperate for money to pay creditors back home.
District Judge Soh Tze Bian said the custodial threshold had been crossed as there was a need for general deterrence.
The offence, he said, was clearly planned and premeditated, and Mok's actions, calculated and deliberate.
"Instances where the WhatsApp service is being used as a tool to perpetrate offences are undoubtedly on the increase throughout the world.
"In IT-savvy Singapore, the problem is further compounded by the wide and extensive reach of the WhatsApp service and other similar apps on smart mobile phones," said the judge.
"Elderly and young persons of the fairer sex are made particularly vulnerable by this exposure, as they are most likely to be preyed upon and solicited for sex and/or held to ransom," he added.
He also pointed out that crimes involving the smartphone were easy to commit and might be much harder to detect and prove.
Judge Soh noted that Mok even had the audacity to negotiate with the victim. He appeared to be very confident of the threat he had made and was bold enough to come to Singapore to collect the sum.
Mok could have been fined up to $5,000 and jailed for up to six months.