You don't hear the expression get your dander up very often nowadays, but it's too good a piece of English to allow to die. It means to get very angry.
Anyway, don't. Take some deep breaths. Imagine what fun you'll have telling your friends all about it. Pretend the idiot people are chipmunks (I seem to remember that's What Katy Did).
And if possible keep your distance!
Thing Not To Do Today: get your dander up. People aren't quite sure about this expression. It could mean attacking someone so ferociously that dandruff flies about in all directions (dander=dandruff) .
Or, more likely, it's from the dander which is the frothy stuff you get on fermenting cane juice when you make rum: so it's rather like boiling with rage.
This meaning is probably from the Spanish redundar, meaning to overflow, which is from the Latin redundāre, to flow backwards.
There are a few other similar expressions, come to think about it: people can get airated (or aerated, or even aeriated); or sometimes they have steam coming out of their ears; or they can even blow their tops!