Depends on if I have to work that day or not (or If I am sick enough to warrant calling off in the first place).
If I have to work, I take some mild meds(A lot of cold/allergy medicine knocks me out, even the "non-Drowsy" kind) and push through, using being whiny and talking in my Batman voice. I tend to lose my voice when I get sick.
If I don't have to work, or feel bad enough to call in, I'll take some strong meds to knock my ass out and I sleep it off. Once I get to the point where I can't force myself to sleep I'll usually make some soup and start gaming, and carry on like a normal day off, minus going out of course.