hens' teeth

Something very scarce (because hens have no teeth). Typically used in phrases like "rarer than hens' teeth." I can hardly believe your brother got an A on his final exam—grades like that are rarer than hens' teeth for him!

Common Names:

Name	Pronounced	Usage
Youta	yo:-tah	Japanese
Malle	-	Medieval English
Carson	KAHR-sən	Scottish, English
Nicola	['nikələ]
AmÍLcar	-	Portuguese, Spanish
Celestine	SEL-əs-teen	English