Mental/emotional boredom, and have to wait longer than I should.
A fail-safe way to drive me into a rage is to force me to wait for something I really want. And I can turn into a fucking beast.
They probably have the same root cause, which is that I need stimulation all the time, and that means something has to be going on in my life - there needs to be change, motion, energy. Being starved of purpose is very unhealthy for me, in the same way not having food might be for many people. I actually mean this less in an external than an internal sense...I could be lying in bed, but have an active mind that is in use, experiencing strong emotions.
I tend to have trouble getting to sleep at night because my brain will not shut down.
People who "get" me are extremely, extremely hard for me to come by. I can't stand people who fuck with the ones who "get" me just for the sake of some bullshit short-sighted utopian vision. This, for me, is unforgiveable.