一回生，二回熟 [－－－－－－－]

Jyutping jat1 wui4 sang1 ， ji6 wui4 suk6
Pinyin yī huí shēng ， èr huí shú

Definitions (Wiktionary)
  1. phrase, idiomatic
    first time awkward, second time skillful; difficult at first, easy later on
  2. phrase, idiomatic
    first time strangers, second time friends; to soon get to know each other