Cut off your arm. Of course, this can only work twice.
HA HA!
You can imagine being sick, and actually become sick, I've heard.
Thats what I used to do when I was in school and wanted to go home up until 12 grade when I just left.

If I didn't want to go it was easy. Both my parents couldn't be gotten ahold of at work so I would unplug the answering machine and go do whatever. My parents would never know because the school had no way to tell them.