don't teach your grandmother to suck eggs

don't teach your grandmother to suck eggs

An older person is wiser and more experienced and worldly than a young person may think—thus, the older person does not need to be taught. I may be 70, but I've been using a computer since before you were born! Don't teach your grandmother to suck eggs, sonny!
See also: egg, grandmother, suck, teach
Farlex Dictionary of Idioms.
See also:
  • biggest frog in the puddle
  • one man's meat is another man's poison
  • may as well
  • may/might as well
  • May I speak to (one)?
  • May I speak to ? Go to Could I speak to
  • come what may
  • take up (the) cudgels against (someone or something)
  • take up the cudgels
  • sell in May and go away