You don't get it.
It is an act - to pretend that what has been said is so disgusting it has turned the person's stomach - thus no polite person would think it polite to discuss the topic - and thus no discussion.
It is done for the purely passive aggressive reason that the person cannot support a rational discussion of the topic, so they throw the smoke screen of the irrational response.
Diva's Husband
I'm sorry I wasn't clear - I do get it and agree with you. Often when I encounter this in real-life I nicely (but pointedly) ask about the person getting nauseated, light-headed, or otherwise physically repulsed.
After some coaxing I get them to admit that they didn't literally get ill. I do it for fun!
In any case, their hypersensitivity is clearly incongruent with their rhetoric about being tough. Things usually get hot when I get into that! ;-)