know (one's) beans

To be knowledgable about and/or very familiar with something. I had no idea you were such a good piano player—you really know your beans!

Name	Pronounced	Usage
Wil	WIL (English, Dutch), VIL (Dutch)	English, Dutch
AdÉLaÏDe	a-de-la-EED	French
Manuele	mah-NWE-le	Italian
Lucy	['lu:si]
Batya	-	Hebrew
&Thorn;ÓRgeirr	-	Ancient Scandinavian