give one's head a shake

present singular third person gives one's head a shake · participle present giving one's head a shake · past gave one's head a shake · participle past given one's head a shake

1. CanadaidiomaticTo reassess the common sense of one's behaviour, ideas, etc.

   Talk about focussing on the unimportant. Give your head a shake, Google.

   2011 December 5, Cam Cole, “Leafs lying scandal blown out of proportion”, in National Post

   2 more examples

   If you're thinking about topping your burger with ketchup, mustard, relish and perhaps a couple of pickle slices, you might want to "give your head a shake."

   2009 August 20, Joanne Chianello, “New program asks you to pass on the sodium”, in The Windsor Star

   But give your head a shake, people. Stop pushing for Wi-Fi at campgrounds around B.C. The entire premise of going camping is to escape from the hustle and bustle of our busy lives.

   2011 August 19, Roxanne Hooper, “Please, keep the wilderness wild”, in The Record, New Westminster, British Columbia