逞英雄当小丑
[chĕng yīng xióng dāng xiăo chŏu]
It's like someone who tries too hard to be a hero but only ends up making a fool of themselves. 'Cheng Yinxiong Dang Xiaozhou' literally means 'act as hero end up clown', reflecting self-mockery on showing off unnecessarily which often brings embarrassment instead of respect.