The word "咧咧" is formed by reduplicating the character "咧", which itself is a pictophonetic character composed of the mouth radical (口) on the left, indicating association with speech or sound, and the component "列" on the right, primarily providing phonetic guidance. This reduplication emphasizes the action's continuous or repetitive nature, resulting in a word that typically denotes idle, incessant, or nonsensical talking, as used in colloquial phrases like "瞎咧咧".