冇咁大個頭就唔好帶咁大頂帽 [－－－个头－－－带－－顶－]

Jyutping mou5 gam3 daai6 go3 tau4 zau6 m4 hou2 daai3 gam3 daai6 deng2 mou6
Pinyin mǎo gān dà gé5tou jiù wú hǎo dài gān dà dǐng mào

Definitions (CC-CANTO)
  1. one can only spend as much as one can afford; one should not over stretch beyond their limits / power / abilities; to not bite off more than one can chew [colloquial]