Teach your grandmother to suck eggs

Pro Tip 1/3

Older Expertise

Use when someone older or more experienced is told something they already know.

Explaining the tax system to Aunt Mary, a retired accountant, was like teaching your grandmother to suck eggs.

Pro Tip 2/3

Potential Offense

It might offend if implying someone's advice is unnecessary.

When I corrected his email etiquette, he snapped back, 'Don't teach your grandmother to suck eggs!'

Pro Tip 3/3

Cultural Humor

This phrase can be humorous, especially when self-applied, mocking one's own overconfidence.

I tried lecturing about classic cars until I realized I was teaching my grandmother to suck eggs.