Knee-slapper is an idiom that has been in use for less than 100 years. An idiom is a commonly used 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 common in American slang or British slang, is essential for the English learner. Many English as a Second Language students do not understand idiomatic expressions and idiomatic language such as hit the sack, 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, common expressions, colloquial terms, and popular expressions to memorize that are used figuratively or idiomatically. We will examine the meaning of the common idiom knee-slapper, where it came from, and some examples of its idiomatic usage in sentences.

A knee-slapper is an uproariously funny joke; the idea is that the joke is so funny, one collapses into laughter when one hears it, slapping one’s knee. Knee-slapper  is a hyphenated compound word, which is a word derived from two or more separate words used together with a hyphen to create another word. Compound words are new words that have a different meaning from the definitions of the original words. The expression knee-slapper is American; it came into use in the mid-twentieth century.


Not exactly a knee-slapper in a different context, but this quote drew laughter from audience when DeVillers refused to bite on a bit of gamesmanship from a reporter trying to get him to break prosecutorial protocol. (Columbus Monthly)

Not to be outdone, Francois Legault’s government last week came up with a knee-slapper of a plan to give a subsidy to every Quebecer with a driver’s licence. (Montreal Gazette)

And repeating a real knee-slapper ranks high among life’s basic joys. (Reuters)

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