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
Midas	MIE-dəs (English)	Greek Mythology
Hallvar&Eth;R	-	Ancient Scandinavian
Piety	PIE-ə-tee	English (Rare)
Hewie	HYOO-ee	English (Rare)
Brahma	BRAH-mah	Hinduism
Cary	['kɛəri]