LONDON: BlackBerry users, who secretly watch porn on their new smartphone, could be in for a nasty shock as a new built-in feature tells all their friends about the naughty habit.

The 'Show what I'm listening to' feature has been designed for users, who are fond of sharing music videos or funny YouTube clips, the Sun reported.

But contacts of some people were alerted while they were secretly viewing porn on their Z10 smartphone. A user, named Sosof, posted a screenshot of his pal viewing an adult site, on the Crackberry web forum.

"Be very careful! LOL," he said with the picture. Another user, Gbolhajo added that this had happened a lot of times to his contacts as well.

The mobile company said the feature, which will also run on the new Q10 phone out on Monday, must first be turned on. However, some users have claimed that it was already activated and they had to turn it off themselves.