司仪当场发飙用英语可以表达为 "The MC flew into a rage on the spot" 或 "The MC had a sudden outburst of anger on the spot."
"Fly into a rage" 是一个常见的习惯用语，意思是突然发怒，暴躁的行为。"Outburst of anger" 意思是突然的愤怒反应。
举个例子：
The MC flew into a rage when the microphone stopped working.
(当麦克风停止工作时，司仪当场发飙了。)
The audience was shocked when the usually calm MC had a sudden outburst of anger during the ceremony.
(观众惊讶地看着通常沉着冷静的司仪在仪式上突然发怒。)