丈二和尚，摸不著頭腦 [－－－－－－－着头脑]

Jyutping zoeng6 ji6 wo4 soeng2 , mo2 bat1 zoek6 tau4 nou5
Pinyin zhàng èr hé shang , mō bu zháo tóu nǎo

Definitions (CC-CEDICT)
  1. lit. like a three-meter high monk, you can't rub his head (idiom)
  2. fig. at a total loss