Daily Chinese Idiom Guessing Game
To be caught off guard or unprepared for a sudden event.
措手着手处理。来不及动手应付。指事出意外，一时无法对付。
元·无名氏《千里独行》楔子咱今晚间，领着百十骑人马，偷营动寨，走一遭去，杀他个措手不及。”
The sudden rainstorm caught us off guard, and we got soaked.