Have/be on a short fuse
Definition 1 of 1
Pro Tip 1/3Emotional Charge
This phrase emphasizes strong, sudden anger; trigger words or situations ignite emotions rapidly. 
After waiting hours, customers are on a short fuse; any delay might cause uproar.
Pro Tip 2/3Informal Expression
Used mainly in casual conversations, it's not suitable for formal writing or speeches. 
In meetings with our boss, we avoid sensitive topics as he can be on a short fuse.
Pro Tip 3/3Behavior Warning
Often used to caution others about someone's mood, suggesting they act with care. 
Give Joe space to cool off; he's been on a short fuse since this morning.