The real reason behind Bollywood actors turning down Rakeysh Mehra's Delhi 6 is believed to be a masturbation scene.
Hrithik Roshan was first happy to star in the movie, which is believed to be an autobiography of Mehra himself, but when he heard of the masturbation scene - he turned it down.
Mehra then approached Ranbir Kapoor, Siddharth, and Aamir Khan's nephew Imran Khan, all of whom objected to the scene.
It is now rumoured that Abhishek Bachchan is expected to take on the role, with Sonam Kapoor to star opposite him.
http://www.radiosargam.com/films/archives/8975/masturbation- scene-made-hrithik-refuse-a-film.html
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