There used to be a Mac program for this situation ("There's an app for that!", right?) You start the program and it counts down from 10. At zero it disables sl

There used to be a Mac program for this situation ("There's an app for that!", right?) You start the program and it counts down from 10. At zero it disables sleep, and displays a warning screen stating that the computer is alarmed and should not be moved by anyone but the owner. When the owner returns, he enters a password to end the program. If anyone tries to move the computer in his absence, the vibration sensor triggers a screeching alarm.