Oops! Before you let your imagination fly, here is the actual story...
Ranbir Kapoor along with director Imtiaz Ali and crew members of the film Rockstar had apparently visited the brothel at Grant road in Mumbai to shoot a sequence in the film that features Ranbir playing the guitar and singing to an audience of sex workers.
According to a leading newspaper, Imtiaz Ali was keen on shooting a particular scene in Rockstar in an actual brothel to give the scene a more authentic look.
The sex workers were apparently very excited to meet Ranbir Kapoor and nervous at the same time about facing the camera. However, they soon relaxed once Imtiaz and Ranbir spent some valuable time chatting with them and making them comfortable.
The sex workers were very cordial and even served the crew members of Rockstar their traditional breakfast - chai and pav!