As Jack is his favourite actor, the star had it on his mind while working on his character's trademark guffaws.
Earlier, the actor's bald look was said to have been inspired by Marlon Brando's style in Apocalypse Now!
PS: When Dutt shaved his head, his twins Shahraan and Iqra stayed away from him as they couldn't recognise him! They took a while to recognise their bald dad and that too only upon hearing his voice.