縮頭龜 [缩头龟]

Jyutping suk1 tau4 gwai1
Pinyin suō tóu guī

Definitions (CC-CANTO)
  1. (noun) a chicken (coward); a coward; a quitter; to describe someone who shies away from difficulties / challenges / responsibilities; to describe someone who pulls out of doing something the last minute
Definitions (粵典–words.hk)
  1. 名詞
    形容​冇​膽​、​遇事​退​縮​嘅​人​（​量​詞​：​隻​）
    a coward; literally: withdrawing head tortoise
    • 俾人凶一凶就即刻匿響個朋友後邊，正一縮頭烏龜。
      俾人凶一凶就即刻匿响个朋友后边，正一缩头乌龟。
      He backed off at the slightest hint of threat, what a coward.