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
Swanhild	-	German
Marni	-	English
Zakchaios	-	Biblical Greek
Janko	-	Slovene, Croatian, Serbian, Slovak
Senka	-	Serbian, Croatian
Odetta	-	English (Rare)