When SPH Chinese radio station 1003FM asked for its listeners to call in with their opinions on "teenagers behaving badly", Mr Chua, had a story to share.

The 37-year-old driver said that he came across a sex clip supposedly involving several local polytechnic students.

When Chinese evening daily Lianhe Wanbao called Mr Chua, he told the paper that he came across the videos while surfing the Internet, when the window popped up on his screen.

He told Wanbao that there were a number of such videos, and he learned from the subtitles that the teenagers in the clips were from Singapore, Malaysia, Taiwan and Hong Kong.

One particular clip involved several female students from a local polytechnic.

Mr Chua told Wanbao, "From the look of the video and how it was flimed, I doubt that the clip was made with an intention to be posted online.

"The videos were probably leaked and uploded by a third party.

"Chances are that the teens in these sex videos are unaware that the clips have been circulating on the Internet."

As for the culprit, Mr Chua already had a suspect in mind - unscrupulous second-hand mobile phone dealers.

"I know that some second-hand mobile phone dealers will search the phones they purchase from customers for illicit material.

They will then rip the photos and videos from the phone's memory cards and put them online."