The Keeper wrote:
My response is that Kirk was simply engaging, distracting Khan, buying time for the Enterprise to finish her repairs. As for his over the top delivery of the 'line', Kirk knew he had to make Khan believe his distress was real, which, as witnessed, he did.
Which is a great explanation.
My problem comes from the folks that act like Shatner's scream was some type of cinematic triumph that should honored with religious fervor or those who complain about having to do mental gymnastics to make Spock's work in their heads when we had to do mental gymnastics for the first one to make sense in the context of the story.
Spock has always been shown to have issues when trying to handle emotional duress. Before the Pon Farr had even gotten remotely bad he was threatening to break McCoy's neck in "Amok Time".