What does “estar de malas” mean in Mexican Spanish?

In Mexican Spanish, estar de malas means to be in a bad mood, grumpy and easily annoyed. The phrase looks like it means “to be in bad ones,” but malas here stands for malas rachas or malas horas: a bad patch. Say hoy ando de malas and people will know to give you space. Its opposite is estar de buenas, in a good mood.

Here the speaker says that without nine hours of sleep she is de malas y gruñona (grumpy) all day. The same phrase can also mean plain bad luck, as in si llueve, estamos de malas (“if it rains, we’re out of luck”), and context tells you which one is meant. With mood, it usually pairs with estar or andar.