chhǐ-bú-chhǐ-chhǔ嗤母嗤呲

to mutter softly or in private

English Wiktionary, “嗤母嗤呲” (CC BY-SA 4.0) — https://en.wiktionary.org/wiki/%E5%97%A4%E6%AF%8D%E5%97%A4%E5%91%B2 · confidence: Medium (Wiktionary)