Fly off the handle
Definition 1 of 1
Pro Tip 1/3Emotional Intensity
The phrase suggests a sudden shift to extreme anger, typically in an uncontrolled manner. 
The calm discussion took a turn when Mike flew off the handle.
Pro Tip 2/3Surprise Element
The anger is often unexpected and may seem disproportionate to the situation. 
She flew off the handle when she saw the typo, which surprised everyone.
Pro Tip 3/3Negative Connotation
Using this phrase usually implies a criticism of the person's reaction as being unreasonable. 
His tendency to fly off the handle made his colleagues wary of giving feedback.