I'm having a bad hair day.
a bad hair day直译过来就是：“今天的发型很糟糕”，这个短语的正确意思是，“很不顺利的一天”。因此，当美国人说"I'm having a bad hair day."时，他/她要表达的意思就是:"I am so unlucky today."、"I'mhaving a bad day."、"I am in a bad mood today."。
Shirley: The boss had a conversation with you just now, right?
Jane: I don't want to say a word now. I think I'm having a bad hair day.
①How's the day? Why are you looking so exhausted?
②What's wrong with you? You screwed up the presentation.
③Are you OK? You mistook men's room for women's room.
④I heard you just got fired.
1. screw up 搞砸
Yes, they have really managed to screw up this game.
Apologize when you screw up and focus on other people, not on yourself.
2. mistake sb./sth. for sb./sth. 把……误当做是……
We often mistake her for her twin sister.
When hay fever first occurs it is often mistaken for a summer cold.