Meaning of hēi hēi:
hēi hēi
嘿嘿
Onomatopoeia
(onom.) he he; mischievous laughter
Tā tīng wán xiàohuà hòu, hēi hēi de xiào le.
他听完笑话后,嘿嘿地笑了。
After hearing the joke, he laughed 'he he'.
Tā tīngdào zhège xiàohuà, rěn bù zhù fāchūle hēihēi de xiàoshēng.
他听到这个笑话,忍不住发出了嘿嘿的笑声。
He couldn't help but let out a mischievous laugh upon hearing the joke.