Explanation: Dancing with an ax in front of Luban Gate. It is a metaphor for showing off one's skills in front of experts and not overestimating one's abilities.

From: Tang Dynasty Liu Zongyuan's "Wang Brothers Singing Poems Preface": "Using the ax at the gate of Ban and Ying,

Si Qiang Yan'er." Song Dynasty Ouyang Xiu "With Mei Sheng" "Yushu": "Yesterday I was in Zhending, and there were seven or eight poems. Now I've recorded them, and I'm playing with my axe. It's ridiculous."

Pronunciation

bān mén nòng fǔ

I heard that Sister Tingting was very knowledgeable, so how dare I do this and talk nonsense with her. (Chapter 52 of "Flowers in the Mirror" by Li Ruzhen of the Qing Dynasty)

He actually showed off his piano skills in front of the piano master, which is really a master of his own craft.