use (one's) noodle

To use one's own intelligence and intellectual ability; to think logically and rationally. ("Noodle" 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 noodle for a change! I can't believe you were arrested for selling marijuana. What were you thinking? Why don't you use your noodle once in a while?