too big for britches

too big for one's britches

Rur. too haughty for one's status or age. Bill's getting a little too big for his britches, and somebody's going to straighten him out. You're too big for your britches, young man! You had better be more respectful.
See also: big, britches

too big for (one's) britches

Overconfident; cocky.
See also: big, britches