ぺちゃぱいMeaningsNoun1. flat chest; small breasts (Colloquial)Other readingsペチャパイぺちゃパイExamples1昔むかしはペチャパイだったのに、いつの間まにかこんなに大おおきくなりやがって。She used to be flat-chested - just when did she get so large?