Sources say, Kapil Sharma had not informed John about it as he wanted to capture the actor's natural reaction at being slapped.
An informer from the sets says, "When Zarinaji slapped him, John's shocked expression worked well for the scene."
Says Kapil Sharma, "I wanted the scene to be as natural as possible and we decided to go ahead and keep John in the dark. John's expression was exactly what we were looking for."
In fact we learn that even Zarina was a bit skeptical when she was told she would have to slap the actor without his knowledge. Producer Goldie Behl says, "After much convincing she went ahead and gave the shot."