嘴在逞强身却投降
[zuĭ zài chĕng qiáng shēn què tóu jiàng]
This nickname conveys a contradictory state of a person whose words seem to be strong but deep inside they've already given up. It's often used by someone who wants to appear brave and defiant, yet their body language or actions reveal a more vulnerable side, implying a struggle with vulnerability.