bad hair day
noun [ C ] informal uk/ˌbæd ˈheə ˌdeɪ/ us/ˌbæd ˈher ˌdeɪ/
很不顺利的一天，倒霉的日子
a day when you feel that you do not look attractive, especially because of your hair, and everything seems to go wrong
I'm having a bad hair day. 我今天不走运。