Flap one’s gums is an idiom. 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 flap one’s gums, where it came from, and some examples of its idiomatic usage in sentences.
Flap one’s gums means to babble, to talk incessantly, to say a lot of words that have very little meaning. The expression flap one’s gums came into use in the United States in the mid-20th century and references a constantly moving mouth. Related phrases are flaps one’s bums, flapped one’s gums, flapping one’s gums.
Don’t flap your gums about partying with hot girls in the Hamptons if you’ve never even driven through Long Island. (New York Post)
Most of you flap your gums about other people but you’re still stuck in your seats. (Christian Post)
He flapped his gums all the time about being proud to be different, but in his heart of hearts, ooh, that man is cocky. (Entertainment WEekly)