Ah, the sick day. When you should be at home getting better but instead, you work; possibly prolonging your illness and infecting others. Because you are too, too important. Hi ego, thanks for coming to the party.
And before you think I am criticizing other people, I am an offender. And I'm in good company.
According to a survey (Boo NPR for not linking to the survey), hourly folk hustle it into work while they are sick due to lost wages and for many/most of the rest of us, it's because we doubt we are "sick enough." OMG, that is totally me. Whoah, dude...evidence of writing whilst sick when I should be taking a sick day. In my own defense, I can work from home. That's not to say I haven't gone in when I shouldn't but I can always find a way of getting some work done, despite better judgment.
(I've also written a little on the crap reasons for staying home sick)