be caught with (one's) trousers down

be caught with (one's) trousers down

To be taken by surprise; to be caught in a vulnerable (often embarrassing) position or situation. When the boss started firing questions at me, I was caught with my trousers down and looked like a fool. I just hadn't considered all of those potential outcomes yet and didn't know what to say. We seriously underestimated our opponents on Saturday and were caught with our trousers down.See also: caught, down, trouser