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
Fidelia	-	Spanish (Rare)
Odilia	-	Ancient Germanic
Lloyd	LOID	English
Chikondi	chee-KON-dee	Southern African, Chewa
Lavina	-	English
Ju	-	Chinese