Meaning:

This term, literally translated as “costal cartilage” and referring to strips of cartilage connecting the rib bones to the breastbone, is a metaphor in the Chinese language for a person or object’s weak point, which can easily be placed under attack.

Example:

A: 丽丽说她的男朋友总是放她鸽子，说了好多次要和他分手，怎么他俩还在一起？

Lìlì shuō tāde nánpéngyou zǒngshì fàng tā gēzi，shuō le hǎoduō cì yào hé tā fēnshǒu，zěnme tāliǎ hái zàiyīqǐ？

Li Li says her boyfriend often stood her up and she would break up with him. Why are they still together?

B: 丽丽的软肋是喜欢听甜言蜜语，又喜欢帅哥，所以对方一说好话，丽丽又心软了。

Lìlì de ruǎnlèi shì xǐhuan tīng tiányán mìyǔ，yòu xǐhuan shuàigē，suǒyǐ duìfāng yī shuō hǎohuà，lìlì yòu xīnruǎn le。

She is a sucker for sweet talk and good looks. Every time the dude tells her sweet words, she will melt and forgive him.