是某人自己的责任,是某人自己的事
be sb's lookout
(认为某人的行为不明智)是某人自己的责任,是某人自己的事
used to say that you do not think sb's actions are sensible, but that it is their own problem or responsibility
If he wants to waste his money, that's his lookout.他要乱花钱,那是他自己的事。
释义来自《牛津高阶英汉双解词典》第 9 版