out of the corner of one's eye
Glancing casually or surreptitiously, as in Out of the corner of my eye I saw Justin walking out the door. This expression refers to looking sideways at something rather than directly.
Words nearby out of the corner of one's eye
out of sorts,
out of square,
out of step,
out of stock,
out of the blue,
out of the corner of one's eye,
out of the frying pan into the fire,
out of the frying pan, into the fire,
out of the hole,
out of the loop,
out of the mouths of babes