can of worms idiom informal
一堆麻烦事；棘手的问题；复杂而难解决的问题
a situation that causes a lot of problems for you when you start to deal with it
Corruption is a serious problem, but nobody has yet been willing to open up that can of worms. 腐败是很严重的问题，可是还没有人愿意触及这个难题。