I dare you to knock it off--and anybody that'll take a dare will suck eggs.
teach one's grand-mother to suck eggs; don't show off your minor skill to an expert
He is always telling the director how to run the business; that's like teaching his grandmother to suck eggs.
Rather than teach my grandmother to suck eggs, I would like to teach myself to suck in new knowledge.
Never teach your grand-mother to suck eggs.
