DON'T TEACH YOUR GRANDMOTHER TO SUCK EGGS.
Don't teach your grandmother to suck eggs.: translation
Don't teach your grandmother to suck eggs.
Prov. Do not try to instruct someone who is more experienced than you. (Extremely casual; potentially rude.) •
Bob told the seasoned guitar player that she was holding the guitar incorrectly. “Don't teach your grandmother to suck eggs,” she replied.