More info revealed about the song-
http://www.indiatimes.com/entertainment/its-been-17-years-of-srks-chaiya-chaiya-and-farah-khans-made-some-major-revelations-about-the-song-243791.html
When Farah revealed the change of the shoot location of the song to SRK, she clearly specified that no compromises would be allowed. Farah told SRK that he would have to jump, prance, go down on his knees, and do everything that was expected of him at ground level. Recollecting the conversation with SRK, Farah revealed "Shah Rukh was game, promising that he'd kill it for any other actor. He was enthusiastic and super energetic, refusing to wear a safety harness and even threatening to dance on top of the engine room till I pointed out that the gushing steam would burn him. As it is, at the end of each day, we'd be covered in soot, with pieces of coal clogging our noses, ears and stuck to our hair!"
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