The injustice or offensive condition becomes such an outrage that one cannot contain oneself and you have to do whatever you need to do to put a stop to the injustice or offensive condition
Sometimes, it can be caused by even less. For instance when you had an extremely taxing weekend with a lot of social stuff (in hindsight, i overbooked it), and during lunch at work someone (once again) mentions that there's some patte in the corner of my mouth.
Reflecting on what happened after that comment was uttered, i can only describe the mind-proces as; shock that i forgot, and the realisation that the mouth-corner-thing happens to me quite often. Confusement on what the appropriate reaction is, because i was still processing the weekend in my head. The comment came at the worst possible time, i was contemplating something and was completely unprepared for it.
After the shock at the intrusion and still figuring out what the appropriate reaction is I grew frustrated, but i knew that was the wrong reaction, it went to wanting to cry because of the frustration, but i stamped that down, because that was the wrong one as well. So, I was frustrated but didn't want to cry. It wasn't a joke, but a sincere comment so there really is no reason to be frustrated. Then I grew angry with myself because i couldn't figure it out. Then frustration because i thought i had this under control, then anger.
And at that moment it turned into sheer terror at being unable to cope with it. I stood up too quickly, throwing back my chair in the proces, turned on my heels and ran out of the kitchen and locked myself up on the toilet. I was in disbelieve on what just happened, and more importantly wondering wtf just happened and what caused me to lose control like that for the first time after 6 years of being able to keep it under control.
A high-pressure cooker with no release valve.
---------------
In a talk later, I was described as storming out of the kitchen and slamming the door behind me, scaring the crap out of a friend and weirding out my co-workers. I do not remember slamming the door. I thought I ran, but apparently i stormed off with the most violently angry face they'd seen on me ever.
The proces i described above, from the initial well-meant comment to me storming out; 4 seconds.
(And just right now, i finally get a quote of someone uses to describe himself: From 0 to insanity in 3.578 seconds).
And I hate what happened. It took me 2 weeks of explaining to a friend and manager what happened, and that I was as honestly as weirded out by it as them, before it got accepted as a fluke happening due to excess stress. Ofcourse with the comment that I better be normal next time
P.S.: I didn't even now of Asperger when that one happened.