[File photo]

Such risky methods of IOU is found usable on several online lending platforms, but it is usually more often accepted within the QQ group chats connected to such platforms. Borrowers are also required to upload pictures of their ID cards and report their family information, including their address and cell phone numbers.

Once a clear photo of a naked borrower holding his or her ID card is uploaded to lenders, he or she can get up to 15,000 yuan ($2,277) credit with a maximum of 36 month installments, the Nandu Daily reported.

The credit varies based on the borrower's education background. Usually an undergraduate student can receive 15,000 yuan in credit, while those studying at famous universities as well as doctorate students can receive even larger loans.

What comes with the seemingly easy business transaction is costly overdue repayment.

According to a self-claimed former borrower Li Li (pseudonym), the weekly interest rate was 30 percent for her 500 yuan borrowed from an online platform in February.

As she kept failing to pay back on set payment due dates, she borrowed more money from the platform with the same weekly interest rate until the overdue payment grew to 55,000 yuan, which then led to a threat with her naked pictures, the Nandu Daily reported.

Li told the newspaper that many of her fellow students have borrowed money in this way, but most were too ashamed to talk.

Snapshots of similar threatening collection messages have also gone viral, with a photo of a female borrower and a message reading how the lender would send the photo and her naked video footage to her family members if she could not pay back her 10,000 yuan borrowed on an annual interest rate of 24 percent within a week.

"Naked IOUs started long ago. Not only university students but many others also borrowed money with nude pictures," an insider surnamed Zhang told Nandu Daily.

Another Chengdu-based insider said naked pictures are often acceptable as IOUs in underground private loans companies and borrowers – who are usually loaded with debt – are ineligible at standard companies, but they can get tens of thousands from such underground sources.

By Monday evening, several online lending platforms that secretly offer naked IOUs have issued notices on their QQ group chats to stop receiving nude pictures as IOU, Nandu Daily reported.

[Snapshot of threatening collection message. Photo/Sina Weibo]