Hornet 是黃蜂、胡蜂或者馬蜂。如果一個人不明智地捅馬蜂窩，必然遭到大群馬蜂的叮刺圍攻。所以，stir up a hornet's nest的含義就是：捅了馬蜂窩，惹人說辭或者招來批評的意思to provoke the attack of a swarm of spiteful enemies or spirited critics。

例句：Why are you trying to stir up a hornet's nest? Our office has been managed this way for the last twenty years. Don't waste time complaining about it; you'll just get in a lot of trouble.

你為什么要去捅馬蜂窩呢？我們的辦公室這二十年來一向按照這個方式管理。你別浪費時間去提意見了；你會給自己招惹麻煩的。

又如：The case has stirred up a hornet's nest among the press and the congress. Everyone wants to know how this senior officer got away with stealing all those secrets for eight years before he got caught.

這件案子遭到新聞界和國會的強烈責難，使大家震驚的是這個高級官員怎么會竊取秘密情報長達八年之久才被發現。