"Under the weather"
A: Hey, fancy a beer?
B: Sorry, I feel a bit under the weather and I got a headache.
I'm feeling under the weather, so I'm not going to work.
A: Why didn't you come to work yesterday?
B: I felt a bit under the weather, so I stayed in bed all day.
What does "under the weather" mean?
We say that we feel 'under the weather' when we are a little bit sick or ill.
We often use it when we have a cold, hayfever, or other minor illness. We don't use it for serious illnesses.
It isn't actually about the weather!