Oru Kal Oru Kannadi (transl. A Stone, A Mirror) abbreviated as OKOK is a 2012 Indian Tamil-language romantic comedy film written and directed by M. Rajesh. It stars producer Udhayanidhi Stalin in his acting debut, Hansika Motwani, and Santhanam, while Saranya Ponvannan and Azhagam Perumal play supporting roles. The film's music was composed by Harris Jayaraj with cinematography by Balasubramaniem and editing by Vivek Harshan. The film was named after the song of the same name from Rajesh's film Siva Manasula Sakthi (2009).

The film released on 13 April 2012. It opened to highly positive reviews and became a blockbuster, running for 175 days in theatres. It was eventually released in Telugu as OK OK on 31 August 2012.