I rarely get sick, but sometimes just don't feel like going in to work. Once the thought enters my mind that it'd be more fun to just stay home, forget it; in all but the most extreme cases, I'm not goin' in. For the last job I had, I preferred calling in "sick" by leaving a message. This was only possible if the person who got to the office first hadn't arrived yet. Sometimes I'd have to hurry out of bed to get to the phone in order to ensure this.
When it was 7:30 or later, I'd have to talk to someone in person. This would be preceded by me preparing to sound like I'm sick. I would usually go downstairs so that my wife couldn't hear me laying on it pretty thick (she'd typically be asleep, anyway). Sometimes I'd dial the number and then get cold feet. After a minute or two of composing myself, however, I'd leave a message in which I spoke much slower than usual and sounded much less alert.
Two minutes later, I was a happy camper and went straight to bed with a smile on my face.
I'd sometimes feel a tad guilty about doing this (like a teenage boy after masturbating), but certainly not enough to stop the behavior.
BTW, I bought groceries this afternoon and the total came out to $55.55. That's gotta mean something, right?