'dont teach your granny how to suck eggs'

[mooney_76]

what does the phrase 'dont teach your granny how to suck eggs' mean and where did it come from

[Quizmonster]

Click http://www.worldwidewords.org/qa/qa-tea1.htm for the answer.

[gazzawazza]

I always took it as meaning that coz your granny is meant to be really old she probably hasn't a tooth in her head to call her own.

Consequently she can't chew eggs, so will be an expert on the subject of sucking them. The phrase is of course used to warn you that you're trying to tell someone how to do something, when that person knows more about the subject than you do.