𤗈牙罅 [－－－]

Jyutping sip3 ngaa4 laa3
Pinyin xiè yá xià

Definitions (CC-CANTO)
  1. literally: 'to fill the gap in between the teeth, used as a metaphor to emphazise the smallness or the insignificance of something, that it is virtually of little use or value (so small that it cannot even fill one's gap in their teeth)