牀下底破柴 [床－－－－]

Jyutping cong4 haa6 dai2 po3 caai4
Pinyin chuáng xià dǐ pò chái

Definitions (粵典–words.hk)
  1. 語句
    歇後語​，​下​半句​係​「​撞板​」
    to make a big mistake or to fail, because of ignorance or lack of experience
Examples (粵典–words.hk)
  1. Cantonese
    床下底破柴
    牀下底破柴
    • part of a sandwich pun, literally "to chop firewood under the bed"