take unawares

"That's a good big fall to take unawares."

In such places it is better to use no bait, a little fish oil perhaps excepted, as you will then take unawares many a sly old fellow to whom a morsel of meat, no matter how cunningly arranged, would be simply a signboard of danger.

Sometimes her sudden rush would take unawares a full-fed gannet half-dozing on a rocky ledge.

The fame of his shameful doings had spread abroad, and it must soon come to the ears of the man whom he wished to take unawares.

The first time he had to set about a thing in earnest, he was generally handy at it; he was as difficult to take unawares as a cat.