knock someone for six
knock (one) for six
To upset or overwhelm one, especially suddenly or unexpectedly. Primarily heard in UK, Australia. News of my father's sudden death completely knocked me for six.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
knock someone for sixBRITISH, INFORMAL
1. If something knocks you for six, it shocks or upsets you so much that you have difficulty recovering. The emotional impact of losing a parent can knock you for six.
2. If an illness knocks you for six, it causes you to be very ill and weak for a long time. I picked up a virus that knocked me for six. I lost a stone in weight in two weeks.
3. If someone knocks you for six, they impress you to a very great degree. One day Gary walked in with his sister, Leah, and I was absolutely knocked for six. I'd never seen such a beautiful woman. Note: In cricket, six runs are scored when a batsman hits the ball so that it lands outside the playing area without bouncing. When this happens, you can say the bowler has been hit for six.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012