The four big Khans of Bollywood – Shah Rukh, Aamir, Salman and Saif - together on the big screen. Sounds too good, isn't it? That's exactly what another Khan had wanted to do in one of the songs in "Om Shanti Om". But that was not to be.

Director Farah Khan had reportedly approached the "Lagaan" star to be part of the special song that features 31 stars, all of whom are portraying their real selves. But Aamir refused citing a very tight shooting schedule. However, he promised that he would shoot for a special scene in the movie and would definitely take time off for it.

Aamir is known in the industry for keeping his commitments so Farah was very relaxed. A source said: "When the right time came, she asked Aamir to come and shoot. She was very confident that he would come as it was just a half day's shoot.

But when she approached Aamir, she was taken aback by his response. Aamir turned down Farah saying that she should have informed him with a notice, and that too, a month in advance. Farah is very upset about the issue but is keeping mum."

Since then she didn't approach him again as Aamir has a reputation for his firm decisions. Perhaps, Aamir is too busy with his second production "Taare Zameen Par", a children's film which is slated to release in December.

Now that was all about Aamir. But if rumours are to be believed, even Hrithik Roashan was approached for a cameo in "Om Shanti Om" but even he refused it for inexplicable reasons. Whatever be the reasons behind their decisions, the audience would surely miss the two when they watch 31 cine stars swinging to racy beats in the song in "Om Shanti Om".