Knee and elbow
It is a Chinese idiom. Pinyin is "x ī x í ngzh ǒ UB ù", which means to describe a person with low status and not equal to others. It's from Wang Bo's preface to friends in Shanting, Tang Dynasty.
The origin of Idioms
"Lu Pingyuan and Cao Zijian are able to carry a lot of cars, while Xie Lingyun and pan Anren are able to walk on their knees," Wang Bo of Tang Dynasty wrote
Idiom usage
As a predicate, attribute, adverbial; used of human actions
Examples
I'll see you in the future. The third part of the book "Uncle fan" by Wu Mingshi in Yuan Dynasty
Knee and elbow
on the verge of death or destruction - huò zài dàn xī