The key to faking out the parents is the clammy hands. It's a good non-specific symptom. I'm a big believer in it. You fake a stomach cramp, and when you're bent over, moaning and wailing, you lick your palms. It's a little childish and stupid, but then so is high school.
Life moves pretty fast.
If you don't stop and look around once in a while, you could miss it. This is my ninth sick day this semester. It's getting pretty tough coming up with new illnesses. If I go for ten, I'm probably gonna have to barf up a lung. So, I better make this one count.