With sore throat, headache, swollen glands and that horrible Swollen painful taste that you get just before you get pretty walloped with bug? (not sure why, it always tastes 'green' 
Because, at home the house is in need a tidy, the bedroom is a mess so I will feel more awful, which means I will end up tidying just todo I can then collapse in a heap in a tidy house. Because so much needs doing, and Dh will go out as 'I am sick' and it just won't get done, so I will end p doing it all anyway [martyr emoticon] and won't even have him here making me drinks.
Because at work, I can drink coffee all day, some of which might even be made by colleagues (motors of it if I am honest) because my desk is tidy and so my mind will feel clearer even thou I am sick, and I will be able to do some work and because I might even get some sympathy?
Seriously, this time a few years ago I would consider a sick day for a sore throat, now, work seems appealing.
Half the office is sick, so I am not really spreading anything they have not just given me 