American Heritage Dictionary of Idioms:
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.
don't knock yourself out -
1.(idiomatic, ironic) Don't overexert yourself (in doing something that does not require much effort).
I'll get round to it soonish. — Well, don't knock yourself out!http://en.wiktionary.org/wiki/don't_knock_you...http://forum.wordreference.com/showthread.php...http://forum.wordreference.com/showthread.php...
internet examples:1a) = Don't kill yourself (Don't overexert yourself; don't waste your effort; don't try too hard)
• You can't be both mother and father to your kids, so don't knock yourself out trying.
• Give it a shot, but don't knock yourself out.
• However don't knock yourself out working on an animation unless you REALLY want to because an ambitious, time-consuming entry won't guarantee a win.
• Don't knock yourself out trying to keep a lawn weed free.
• Don't knock yourself out trying to be clever. Remember all of those jokes about lame pickup lines. That's because they're usually forced ...
• You'll never get a crusting smoothness so don't knock yourself out trying, but it will look smooth enough.
• So in other words, don't knock yourself out trying to fix your server and network because the fault is in the Touch.
• Not everyone is going to love you all the time so don't knock yourself out trying to obtain everyone's approval all the time.
• don't knock yourself out trying to achieve perfection if the composer doesn't want it in the first place
• If you know the landlord has this reputation, then don't knock yourself out trying to leave the place immaculate.
• Don't knock yourself out doing something that doesn't have to be done.
• My biggest piece of advice--which may be coming too late--is don't knock yourself out doing everything by hand and too much food and too ...
• However, if you do get a job, don't knock yourself out doing all the housework etc as well, let some of it go, and if your husband complains ...
• It really is worth doing if you make it part of the holiday - i.e. - don't knock yourself out doing too much driving each day.
• Don't knock yourself out looking for one, but get the contact info if you run across one. Thanks a lot.
• Don't knock yourself out looking for exact numbers though, just be in the general range.
• But don't knock yourself out looking for any of these. I give substitutes in the recipe. 1b) (ironic/sarcastic) = Don't strain yourself(Don't try too hard there doing almost nothing; Even that tiny effort is evidently too hard for you)
• It means to work or try so hard that you exhaust yourself (as if you were knocked out by a blow). ... So you might say sarcastically "don't knock yourself out" to someone who is not trying very hard.
• HEY DON'T KNOCK YOURSELF OUT FEDERAL ETHICS COMMISSIONER! A citizen is required to potentially spend tens of thousands and open himself to the possibility ...
• What the Khmer Rouge did relatively? THEY BRUTALLY MURDERED MILLIONS OF INNOCENT PEOPLE! But, hey, don't knock yourself out.
• We have a disco once a year (Oh wow! Don't knock yourself out and have too much fun!)
• "Yeah. What are you up to today? We're going to church in a bit."
"Oh, I don't know. Just hanging around here. There's football on
"Wow, don't knock yourself out with all that excitement!"
• Jermaine sounds like a typical adult "boomerang son" who still lives with his mother, insisting he does so only because he's helping her out. About 99 times out of 100, if you ask such people exactly how they're helping their mothers, they stammer something about taking out the trash to the curb every Monday. Wow, don't knock yourself out there.
• Don't knock yourself out actually contributing something worthwhile to the world!
• Yeah, don't knock yourself out actually providing sources or anything.
vs. (if I understand correctly)2a) = Enjoy yourself; go ahead
2b) (ironic/sarcastic) = Well, if you insist
(?)(Lotsa luck/Rotsa ruck; Have at it (if you must); Feel free to try (but I don't think much of the idea) ...)