hit/knock somebody/something for six
hit/knock somebody/something for ˈsix(British English)
1 (often of something unpleasant) surprise somebody a lot: It really hit me for six to find that my father had written about me in his book.
2 completely destroy a plan, an idea, a suggestion, etc.; knock somebody/something over/down: The stock market crash has hit the economy for six. ♢ Toby took a step backwards and knocked the vase for six.
In cricket, if you hit the ball a long distance you score six runs.