老襯當旺 [－衬当－]

Jyutping lou5 can3 dong1 wong6
Pinyin lǎo chèn dāng wàng

Definitions (粵典–words.hk)
  1. 語句
    指​新手​或​笨拙​嘅​人​響​技​術​落​後​情​況​下​，​靠​住​運氣​贏出​；​當旺​即​係​運氣​好
    beginner's luck, or a fool's lucky break