Inspired by this question: How to mess up a PC running Windows 7?, I'm interested in repairable ways that you could intentionally 'mess up' a Mac computer.
Note from a Mod on the other question, that should also be mentioned here:
If you suggest ways to disable/break the computer, please include information on how to fix whatever it is you're breaking as well, if it is not immediately obvious.
One-liner answers, that fail to explain how they work or what the do, will be converted to comments.