turn turtle

get one's knickers in a twist

To become overwrought or unnecessarily upset over a trivial matter.

turn one's color

To change color, especially to become pale or red in the face.

lose one's cool

To become upset or disconcerted; to lose one's temper.

get bent out of shape

To take offense; to become angry, agitated, or upset.

throw a fit

To become angry, enraged, or upset; to act or react with an outburst, …

go south

To become unfavorable; to decrease; to take a turn for the worse.