Unawares

George began to climb all unawares.

The news caught us completely unawares.

If he forks, he will soon catch you unawares.

Your question catches/takes me unawares, I don't know the answer right now...

And I with these untoward thoughts had striven, / I saw a Man before me unawares: / The oldest Man he seemed that ever wore grey hairs.

I'm afraid I've taken the wrong coat, unawares.