That punch was a voice over introducing the characters in the film. So impromptu he penned down the script and then dubbed it in his own voice and in his special style!.
CHILLAR PARTY, releasing on 8th July 2011, is a fun film about a gang of innocent yet feisty kids from Chandan Nagar called Encyclopedia, Jhanghia, Akram, Secondhand, Panauti, Silencer, Aflatoon and Shaolin in whose lives enter two strangers Fatka and Bheedu and how things revolve around their lives making each other an inseparable part of CHILLAR PARTY. The film is co-directed by Vikas Bahl and Nitesh Tiwari.
Here's what Salman Khan wrote for the film:
Suna hai Bade bade sheheron ko chottey chottey bhai log hi chalaate hai....