What sucked about faking being sick to leave school early is that you had to keep the ruse up throughout the entire process.
For example, you had to fake being sick to get out of class. Then, you had to put on a show for the nurse. Then, you had to sound sick when you called home. Then, you had to act sick while waiting to get picked up. Then, you had to act sick on the way home, and then for the rest of night. Hardly seems worth it in retrospect, unless part of your plan was to stay home the next day, too.