嘀咕

他一个人在那儿嘀咕

tā yí gè rén zài nàr dígu

He mumbled to himself there.

别在背后嘀咕别人

bié zài bèihòu dígu biérén

Don't mutter about others behind their backs.

她嘀咕了两句就走了

tā dígu le liǎng jù jiù zǒu le

She muttered a couple of words and left.