get your dander up
get (one's) dander up
To become annoyed or angry. Don't get your dander up with me—I'm just trying have a conversation here. I know I got my dander up a bit last night, so I understand why you're avoiding me.
get your dander uplose your temper; become angry.
The sense of dander in this originally US expression is uncertain, as neither dandruff nor dunder (meaning ‘the ferment of molasses’) seems entirely plausible.