"I want to know what stirs a reaction out of you and why."
Rude surprises.
"Is there anytime in the past where you couldn't control yourself?"
Being hit in the head with a golf club during miniature golf as a kid, and a TKD tournament where everything went wrong one action at a time a few years back. It's moments like that that remind me why my anger is unstable and bad.
It's debatable if I was controlled or not the first time my ex-fiance told me over the phone that she'd cheated on me, as I didn't lash at anything but I responded unstably.
"What actions did you follow through with while like this?"
The golf club case had me black out into a rage. Sobered out of it seeing someone holding me back.
The tournament was pretty much me storming out like some sort of diva once the fights were done (not even sticking around for the medals). Every tournament I've ever gone to has had something go wrong, but that one was exceptional and I'd taken one too many blows to the head during an earlier sword fighting mini-game of sorts they hosted there as well.
The phone call was me going through dizzying angry laughter while saying insulting questions and statements.
I guess hits to the head are a trigger. 
"And finally, what or who stopped you?"
Golf club was my environment, the tournament took time and having to calm down someone else who was pissed off about the tournament for his own reasons during a concussion, and the phone call I recovered from by hanging up the phone.
I am able to control myself quite well. I think I never really had an uncontrolled outbreak of anger/rage.
Well that is probably also because I never really have a reason to... I have never in my life been physically attacked, so I don't know how I would react in such a situation but I belief that I could still control myself.
Also, it would not benefit me in any way to get aggressive because I would not be able to stand up to my "attacker" anyway, due to my physical condition and so on. But it's way more fun to damage the mind then the physical form anyway ^_^ haha ~
Anything and everything.
Yes, several.
Almost choked a store clerk. Threw things around. The occasional "I'll fucking kill you all" threat. Smashed a glass desk to pieces. Fractured my fifth metacarpal in my right hand by banging my fist against a metal archiver-thingy to not hit the guy; didn't flinch until my anger was over. Grabbed some people by the collar to ask the occasional "Dafuq did you say". The usual.
Quite often people who were pulling my leg.
I stopped myself, obviously. I can control it better now.
"Almost choked a store clerk. Threw things around. The occasional "I'll fucking kill you all" threat. Smashed a glass desk to pieces. Fractured my fifth metacarpal in my right hand by banging my fist against a metal archiver-thingy to not hit the guy; didn't flinch until my anger was over. Grabbed some people by the collar to ask the occasional "Dafuq did you say".
Why did I imagine this all happening at the same time XD I'm glad you've got some control over that now. Where did you put all of that anger, perhaps a calming hobbie?
My anger usually soothes with music, playing my instrument, drawing or playing games. Even exercise.
But it is still latent, so it can always come out sporadically in the dumbest of discussions. It hurts the people who get the whip-lash and it isn't really preventable to begin with. All I can do to stop it before I turn Hulk is to pretend I am not hearing them, change subjects, etc.