To have this is to be “up to snuff,” to be wary.

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1852.  It ain’t so bad for one to keep his eyes skinned even in this ’ere civilized country: for thar’s no tellin’, Sargeant, when you may run foul of an enemy.—James Weir, ‘Simon Kenton,’ p. 12 (Phila.).

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1853.  Young man! Keep your eye peeled when you are after the women.—Daily Morning Herald, St. Louis, Jan. 6.

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1855.  We numbered some seventeen members. Our motto was: ‘Keep your eye skinned, and remember Lot’s wife!’Knick. Mag., xlv. 421 (April).

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1856.  A Southern or Western man, Sir, when he goes skewtin’ abëaout, buyin’ goods in bissness heours, keeps his eye-teeth skinned.Id., xlvii. 268 (March).

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1862.  

        You know I ’m a feller thet keep a skinned eye
On the leetle events thet go skurryin’ by,
Coz it ’s of’ner by them than by gret ones you ’ll see
Wut the p’litickle weather is likely to be.
Lowell, ‘Biglow Papers,’ 2nd S., No. 5.    

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1888.  Have to keep your eye skinned, or some darned rascal will get away with all you’ve got.—Texas Siftings, Aug. 18 (Farmer).

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