"Tired" is an excuse that many people use when they look like
crap. Some are legitimately tired, but the amount that are using it as an
honest excuse are dwindling. People also use Tiredness when they are annoyed but don't want to seem like
total jackasses.
Friend 1:
Dude, whatsup with you? You look like crap.
Person: Can you shut up?
Friend 1: What's wrong
man?
Person: Sorry, i'm just tired.