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
Lamar	lə-MAHR	English, African American
Odtsetseg	-	Mongolian
Jovana	-	Serbian, Macedonian
Anita (2)	-	Indian, Hindi, Marathi, Tamil
Andoni	-	Basque
Goraidh	-	Scottish