knock oneself out, to
knock (oneself) out
1. Expend a lot of one's energy or try very hard (doing something). The image is of working so hard as to become unconscious. I'd like to get these reports done before the weekend, but I'm not going to knock myself out.
2. One can feel free (to do something); go ahead; one can do something for as long and as much as one likes. If you want to go through all the files one by one, knock yourself out, but I ain't doing that. We don't get overtime, so there's no reason to stay, but if Joan wants to she can knock herself out.
knock yourself out
Feel free (to do something); go ahead; do something for as long and as much as you like. If you want to go through all the files one by one, knock yourself out, but I ain't doing that.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
knock oneself out (to do something) (for someone or something)
to make a great effort to do something for someone or some group. (As if one had worked oneself into unconsciousness.) I knocked myself out to plan this party for you! She knocked herself out for us. I don't know why I knock myself out to do these things for you. You are not at all appreciative. He knocked himself out to get there on time.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
knock oneself out
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.
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
knock oneself out, to
To make a great effort, to apply oneself to the point of exhaustion. This hyperbolic expression, alluding to knocking oneself unconscious with extreme effort, dates from about 1930. It is often put negatively, as in “Don’t knock yourself out; we can finish this project tomorrow.” In the mid-1900s a newer slang usage surfaced, knock yourself out, meaning enjoy yourself, have fun. Unlike the earlier usage, it is not yet a cliché.
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer