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
Hunberct	-	Ancient Germanic
Antelmo	-	Spanish, Portuguese, Italian
Kai (1)	KIE (German, Swedish, Finnish)	Frisian, German, Swedish, Norwegian, Danish, Finnish, Dutch
Amber	['æmbə]
Baldwin	BAWLD-win (English)	English, Ancient Germanic
GrÁInne	GRAWN-ya	Irish, Irish Mythology