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knock oneself out

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1

Make a great effort, as in I was knocking myself out to finish on time. This expression also is put negatively, Don't knock yourself out, meaning “don't exert yourself; it's not worth that much effort.” [c. 1930]

2

Enjoy yourself, have a good time, as in You're off to Europe? Knock yourself out. [Slang; mid-1900s] Both usages allude to knocking oneself unconscious (see knock out). For a synonym see break one's ass.

QUIZ
SHALL WE PLAY A "SHALL" VS. "SHOULD" CHALLENGE?
Should you take this quiz on “shall” versus “should”? It should prove to be a quick challenge!
Question 1 of 6
Which form is used to state an obligation or duty someone has?
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.

How to use knock oneself out in a sentence

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