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
Heleen	hay-LAY:N	Dutch
Marlene	mahr-LE-nə (German), MAHR-leen (English)	German, English
Estela	-	Portuguese, Spanish
Reynard	RAY-nahrd, REN-ərd	English (Rare)
Betty	['beti]
Eirlys	-	Welsh