use one's head
use (one's) head
To use one's own intelligence and intellectual ability; to think logically and rationally. In this phrase, "head" refers to one's brain. Often said as an imperative. Come on, Dean, I know you can figure this out on your own. Use your head for a change!
use one's head
Think, have common sense, as in Use your head, Martin. No one's coming out in this weather. This idiom uses head in the sense of "brain" or "intellect," a usage dating from the late 1300s.