Let's break down the parts:
* Pipi: This refers to a type of shellfish (pipi clams)
* Hei hei: This is a word that can refer to a necklace or a type of jewelry.
However, the combination of these two words doesn't form a meaningful phrase in Māori.
Could you please clarify what you are looking for? Perhaps you heard the phrase slightly differently, or it's part of a larger phrase or sentence?