Plural of charlie, which can mean a person named Charlie, a foolish person, or in military phonetic alphabet, the letter C.
Charlie as a personal name comes from Germanic 'Karl' (man, king). In military communications, it became the NATO phonetic alphabet word for C, standardized in the 1950s.
Military pilots and radio operators say 'Charlie' for the letter C because it sounds clearly different from other letters when transmitted over static—English chose words specifically to avoid confusion in life-or-death situations!
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