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.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
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’.
Farlex Partner Idioms Dictionary © Farlex 2017