If I'm irritable, I'm quick to anger and the anger turns to rage and fury so fast I can barely keep up with it. Being irritable is not my "normal" self; it's when I'm manic that the irritability starts happening. As soon as I feel chronically testy I have learned to accept that I'm becoming manic.

I think much of this has to do with your baseline...how you are when you're at your most normal.