Knock yourself out is an idiom that came into use in the twentieth century. An idiom is a word, group of words, or phrase that has a figurative meaning that is not easily deduced from its literal definition. Often using descriptive imagery or metaphors, common idioms are words and phrases used in the English language in order to convey a concise idea, and are often spoken or are considered informal or conversational. English idioms can illustrate emotion more quickly than a phrase that has a literal meaning, even when the etymology or origin of the idiomatic expression is lost. An idiom is a metaphorical figure of speech, and it is understood that it is not a use of literal language. Figures of speech like an often-used metaphor have definitions and connotations that go beyond the literal meaning of the words. Mastery of the turn of phrase of an idiom, which may use slang words or other parts of speech, is essential for the English learner. Many English as a Second Language students do not understand idiomatic expressions and idiomatic language such as in a blue moon, spill the beans, let the cat out of the bag, silver lining, back to the drawing board, barking up the wrong tree, kick the bucket, hit the nail on the head, face the music, under the weather, piece of cake, when pigs fly, and raining cats and dogs, because they attempt to translate them word for word, which yields only the literal meaning. English phrases that are idioms should not be taken literally. In addition to learning vocabulary and grammar, one must understand the phrasing of the figurative language of idiomatic phrases in order to know English like a native speaker; it is helpful to maintain a list of phrases and popular expressions that are used figuratively or idiomatically. We will examine the meaning of the idiom knock yourself out, where it came from, and some examples of its use in sentences.
To knock yourself out means to exert maximum effort, to try as hard as you can to achieve a goal. This is the original definition of the idiom, which came into use in the 1930s. The idea is that one is trying so hard to achieve something or is working at maximum capacity to the point of injuring one’s health. However, the idiom knock yourself out took an additional meaning in the latter-1900s. Knock yourself out is now also often used to give someone permission to proceed or to attempt to accomplish something.
By all means work hard but don’t knock yourself out trying to do things that are clearly beyond your capabilities. (The Globe and Mail)
But don’t knock yourself out trying to tie a size 28 bug to hair-thin 7X tippet with frozen fingers. (Field and Stream Magazine)
If selling Chris Nolan’s The Prestige as a fantasy about a good magician (Hugh Jackman) facing off against an evil magician (Christian Bale) who might be an actual wizard gets you that opening weekend, knock yourself out. (Forbes Magazine)
So, knock yourself out if you want to look like a model. (The Sydney Morning Herald)