無所用心 [无－－－]

Jyutping mou4 so2 jung6 sam1
Pinyin wú suǒ yòng xīn

Definitions (CC-CEDICT)
  1. not paying attention to anything (idiom); to idle time away
Definitions (Wiktionary)
  1. phrase, idiomatic
    to not give serious thought to anything; carefree; happy-go-lucky
Definitions (Kaifangcidian)
  1. （沒有對應漢語詞彙）