鲁班门前弄大刀

鲁班门前弄大刀

Literally means:

show off one's skills of carpentry with an ax in front of the gate of Lu Ban, the Great Carpenter

Actually means:

display one's slight skill before an expert

鲁班, a renowned carpenter in ancient China, was said to be the Father of Carpentry.

The phrase literally means show off one's skills of carpentry with an ax in front of the gate of Lu Ban, and it figuratively means showing off one's skills before an expert or a highly skilled person in this field. It is often abbreviated into 班门弄斧. Derogatory.

鲁班，古代有名的工匠，传说是木匠的祖师爷。

鲁班门前弄大刀，在鲁班门前摆弄斧头。比喻在能人或行家面前卖弄本领。常缩略为“班门弄斧”。具有贬义色彩。