know one's stuff

Also, know one's onions. Be experienced or knowledgeable in one's field or in the matter at hand. For example, Patrice knows her stuff when it comes to Mexican history, or We need a handyman who knows his onions. The allusion in the variant is unclear. [First half of 1900s]

Common Names:

Name	Pronounced	Usage
FrÉDÉRique	fre-de-REEK	French
Tarja	TAHR-yah	Finnish
Zosimos	-	Ancient Greek
Yonca	-	Turkish
ValentÍN	bah-len-TEEN (Spanish)	Spanish, Slovak
Virginia	[və(:)'dʒinjə]