Come to think of it, most of my closest friends are Fi. Hmm. Never paid attention to that before.
It used to be when I'd finally lose my temper - and I mean, really lose it - or I got overloaded with upset to the point that I couldn't take it anymore, trying to explain to them "I'm done. Please no more..." was NOT discomfort, it was a matter of my sanity. Whatever was happening had to stop NOW or I was going to disintegrate. I had noticed, while reading "Wuthering Heights", that Catherine, when pressed beyond endurance in a portracted manner by severe emotional pain or things she couldn't rectify, she practically had a seizure. I remember stopping dead at that spot and rereading it over and over because it seemed to "understand" the thing that came over me when I was pushed too far into the red zone for too long a period of time. I also read of Lord Byron (Fe tertiary) having some sort of severe physical response to the very idea of his beloved cousin marrying another man.
These are obviously malignant examples, but they display what I mean by "this has to stop" most perfectly.
It took more than a little time for the Fi users in my life to fully grasp what I meant and to see what I needed. "Back off" or "Stop" wasn't a threat, it was a plea.