when hell freezes over
可能性極低或永遠不會發生的事情
口語·表示某事絕不可能
英文釋義
indicating that something is highly unlikely or will never happen
例句
He'll apologize when hell freezes over — he never admits he's wrong.
典故來源
源自基督教文化,地獄永不結冰,比喻某事絕不可能發生。