"There is no vulgarity in it and it has been flared up... people, who watch the movie, would learn the truth," Aamir said without disclosing any details.
The poster of Rajkumar Hirani's 'PK' features Aamir posing nude with a tape recorder placed strategically to hide his modesty.
Aamir, 49, said that the film, which also stars Anushka Sharma, is the toughest movie of his career.
"I consider this film incomparable to the rest of my films and it is the most important film of my career both in terms of story and my work," he said.
Talking about his hit show 'Satyamev Jayate', which highlights social issues prevalent in India, the actor said he has been working on changes for the third season.
"This season would be different. It will be interactive wherein viewers having questions or suggestions will be able to talk to me during the show," Aamir said.
"Besides this, our team is also working on taking notes of the messages on different social media platforms like Facebook, Twitter, Whatsapp and so on," he added.
Aamir, who was on a two-day visit to the city to launch and oversee a cleanliness drive 'Freedom From Waste', said that there are various problems in the country, which cannot be resolved without active public participation.
"The government or administration alone cannot do anything to resolve them on their own alone unless the public extends its support to them considering those issues to be of their own concern," he said.
Aamir said that if the country is able to deal with waste management, many issues would be addressed automatically.
"For example, if we were able to deal with this menace and make our country waste free, we would automatically have our expenditure and efforts on medical and health reduced drastically," Aamir said.