The word "屁颠屁颠" is formed by reduplicating the two-character unit "屁颠", where "屁" informally implies triviality or silliness, and "颠" denotes a jolting or bouncing motion. The repetition creates an intensified adjectival or adverbial form that describes a person walking or moving in a brisk, lively, and often undignified manner, typically conveying eager or obsequious behavior.