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
Virginia	[və(:)'dʒinjə]
Annushka	-	Russian
MahİR	-	Turkish
Alya	-	Arabic, Indonesian, Malay
Alby	-	Irish
Bruno	BROO-no (German), BRUW-naw (Polish)	German, Italian, Spanish, Portuguese, French, Croatian, Polish, Ancient Germanic