eat one's seed corn

abound in one's own sense

To follow one’s own inclinations and opinions.

ace up one's sleeve

A surprise advantage of which others are not aware.

acknowledge the corn

To admit to the truth of the point at issue or to a mistake; to cop a plea; or perhaps to admit to a small error but not a larger one.

act one's age

To behave in a manner appropriate to one's age.

act one's age, not one's shoe size

Synonym of act one's age (“to behave in a mature manner; to avoid being childish”).

afraid of one's own shadow

Exceptionally timid.

air one's dirty laundry in public

To reveal one's sordid secrets to the public.

air one's dirty linen in public

Synonym of air one's dirty laundry in public.