use your 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! We'll have to use our heads if we're going to have any hope of solving this supply issue.
See also: head, use
Farlex Dictionary of Idioms.

use your ˈhead

(British English also use your ˈloaf) (informal) think carefully; use your intelligence: Use your loaf! Meena can’t read English, so there’s no point in writing her a letter!In rhyming slang, loaf of bread stands for ‘head’.
See also: head, use
Farlex Partner Idioms Dictionary
See also:
  • (from) top to toe
  • (one's) day in court
  • be on (one's) pat
  • (there's) no peace/rest for the wicked
  • at (one's) doorstep
  • at doorstep
  • (one's) jig is up
  • at will
  • at somebody's expense
  • at (one's) expense
References in periodicals archive
Use your head! When you remind yourself that the source of your fright isn't real, the brain sends a calling message to the rest of your body.
What gives you goose bumps?