teach (one's) grandmother to suck eggs

To try to teach an older person who is wiser and more experienced and wordly than a young person may think. Why are you explaining basic typing to Ethel? Yes, she's 70, but she's been using a computer since before you were born—quit teaching your grandmother to suck eggs.

Common Names:

Name	Pronounced	Usage
Neville	NEV-əl	English (British)
Abraam	-	Biblical Greek, Georgian
Coley	['kəuli]
Ripley	RIP-lee	English (Rare)
Elisie	-	Macedonian
Zaal	-	Georgian