The Chinese idiom "自吹自擂" is formed by combining two parallel phrases, "自吹" and "自擂", each structured with "自" (self) followed by a verb: "吹" (to blow) and "擂" (to beat). The repetition of "自" highlights self-directed action, while the verbs metaphorically depict producing sound, like blowing a horn or beating a drum, together conveying the meaning of self-praise.