Definition
To do something to someone when they are not prepared for it, causing surprise or difficulty in responding.
攻其不備
Her sudden resignation caught us all on the hop.
她突然辭職讓我們所有人都措手不及。
The company's sudden announcement of layoffs caught many employees on the hop.
公司突然宣布裁員讓許多員工措手不及。
I wasn't expecting to be asked that question, it really caught me on the hop.
我沒想到會被問到那個問題，這真的讓我措手不及。