Mistake by a grocery clerk. Barista interrupts too many times. Server brings the wrong order.

So that your tightly-wound spring is suddenly released, childishly but vehemently, with a force that's exaggerated in the present context — and all within earshot are shocked.

Granted the annoyance. It's other events have wound the spring so tight. It's the crazyass elevated stress, the 24x7 need for hypervigilance, the certain knowledge that one slip-up or one minuscule gap in your attention can get you murdered.

Until you live in permanent fight-or-flight, and it's not really the clerk or the barista or the server on whom your childishness is focused.