Ex-Rated: Should men fear this app?
10 December 2013 Last updated at 00:56 GMT
Brazil's Public Prosecutor's office has launched an inquiry into whether a new Facebook app "offends the honour" of Brazilian men.
The Lulu app allows female users to rate publicly the men they know. It has 3 million users worldwide, and has clocked up half a billion profile views, according to Lulu.
It has led to a national debate in Brazil about sex, decency and privacy. Mukul Devichand of BBC trending reports.
Follow @BBCtrending on Twitter and tweet using #BBCtrending
Video produced by Dougal Shaw