Daily Chinese Idiom Guessing Game
A person who brings trouble or disgrace to the group, acting as a bad influence on others.
桅马群的劣马。比喻桅社会或集体的人。
《庄子·徐无鬼》夫为天下者，亦奚以异乎牧马者哉？亦去其害马者而已矣。”
He is the one who always complains and spreads negativity at work, a real troublemaker.