At my old job I used to call in sick with the Hantavirus. That was pretty much my recognized way of saying I'm too lazy to go to work.
Later on as a manager I had an employee who would call in sick with "anal glaucoma". First time he did that I asked "what?" and he replied "Anal Glaucoma...means I can't see my ass getting out of bed this morning." I had to respect that. Approved.