Be caught on the wrong foot phrase informal
If you are caught on the wrong foot, you are unprepared for something that happens quickly and unexpectedly.
We were caught on the wrong foot by his financial scandal.
I was caught on the wrong foot when the boss asked the reason why I was absent from work yesterday.
To greatly surprise, shock, or confuse someone
An exclamation of shock or surprise
The phrase "be caught on the wrong foot " is also used in the active form "catch somebody on the wrong foot". Both convey the same meaning.
His question caught me on the wrong foot.