• The teacher threw us a curve when she gave us a surprise quiz.
• I'm angry! I planned to take my vacation next week, but my boss told me that I can't go now. He really threw me a curve ball! There goes all my planning!
• While most interviews are not designed to be stressful, occasionally an interviewer will "throw you a curve" to see how well you respond.
• the once-promising tight end suffered a career-ending knee injury. "God threw me a curve ball," the football player says, in an ironic choice of words.
• A few years ago, however, Kara received some news that threw her a curve. Her spine was twisting laterally at a rapid rate ...
• Life was exciting, until life threw her a curve. Doctors discovered Leanne Patterson had four blocked arteries.
• Mother Nature is throwing us a curve this year
• the fickle fates of boxing threw him a curve
• The timing for the ... event looked fine on paper, but in reality, it threw us for a curve.
• the weather really threw us for a curve. Pleasant overcast conditions prevailed until we reached the top, but just as we started down, thunder, light[n]ing nearby, then light rain, followed by painful hail, then soaking rain ...
• They actually threw me for a curve when I heard their remix because I thought they were going to take it in a completely different direction
• Coming from the NYC area it really threw me for a curve to have so many strangers saying nice things to me as we passed by each other.
• Though Ms. Rowling threw me for a curve at the end. I was forewarned, but I had forgotten about it by the time it actually happened
• It's hard to imagine a career that can throw you for a curve more often than one in radio broadcasting
You need the 'someone': 'throw so. a curve.' There's also a very similar expression 'throw so. FOR a curve' which I would suggest considering at the same time, even if it's probably sort of a mixture of two idioms:
throw so. a curve (as if the person is the batter)
throw/knock so. for a loop (as if the person is the ball)
The meaning is really both to surprise and to confuse, much like 'catch so. off guard' (which BTW is only in LEO in the past tense for some reason); I'm not sure how best to convey that except perhaps by listing both.