Use your noggin!
use (one's) noggin
To use one's own intelligence and intellectual ability; to think logically and rationally. ("Noggin" here is slang for head or brain. Often said as an imperative.) Come on, Dean, I know you can figure this out on your own. Use your noggin for a change! I can't believe you were arrested for selling marijuana. What were you thinking? Why don't you use your noggin once in a while?
Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.
Use your noggin!verb
See Use your head!
See also: use
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.