班门弄斧

zài nǐ miàn qián bān mén nòng fǔ

在你面前班门弄斧。

I'm making a fool of myself trying to show off before an expert like you.

zhēn shi bān mén nòng fǔ le

真是班门弄斧了。

I am ashamed to show off my incompetence in the presence of an expert like yourself.

tā zǒng shì gào sù shàng si zěn yàng jīng yíng shēng yi jiǎn zhí shì bān mén nòng fǔ

他总是告诉上司怎样经营生意，简直是班门弄斧。

He is always telling the director how to run the business and that's like teaching his grandmother to such eggs.