指冬瓜骂葫芦 zhǐ dōngguā mà húlu
[abuse a person by ostensibly pointing to someone else] 表面上骂这个人,实际上骂那个人,近似“指桑骂槐”
你说话说清楚,不要指冬瓜骂葫芦,你看见我的猪吃了哪里的庄稼?