Big B had a surprise visitor at Film City on Saturday when Aamir Khan dropped in to meet him while he was shooting for Balki's Pa with Abhishek Bachchan and Vidya Balan.

Visitors are strictly not allowed on the sets of Pa. But who tells no to Aamir?

Some gauche moments ensued when Aamir showed up. But he was soon escorted to Mr Bachchan's van where the makeup man (none other than Stephan Dupuis who did Robin Williams' makeup in Mrs Doubtfire) was at it for a good four hours.

And then Aamir certifiably became the first person outside the cast and crew of Pa to see the Big B in his startling prosthetic-induced new look.

However there was a price. Aamir was sworn to secrecy literally, that he wouldn't reveal the details of Mr Bachchan's look in Pa to the outer world.

The film's director Balki is paranoid about his leading man's looks leaking out. "We don't allow a single visitor, not even close relatives or friends of crew members on the set. Phones of course are a complete no-no.

The next thing you know the look will be splashed on the net. Aamir of course couldn't be turned down. But yes, we did swear him to total secrecy almost like a boy scout's cross-your-heart kind of pledge.

We can't afford to take any risks. If Mr Bachchan's look leaks out the plot is out. In any case Aamir is a man who knows the exigencies of cinema. He will hardly be expected to leak out the look."

While Aamir was lucky enough to get a dekko at the Big B's unique never-before look, Sanjay Dutt and Ranbir Kapoor who dropped in on Sunday were not that lucky.

While Dutt met up with the B.