give your head a shake(redirected from give one's head a shake)
give your head a shake
An imperative to reevaluate one's ideas, behavior, actions, etc., or to begin acting or thinking sensibly. Primarily heard in Canada. You need to give your head a shake if you really think ghosts exist. Give your head a shake, John—no one is going to pay for a service they already get for free.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.