Single User Mode Questions (mac)

Hello everyone. Completely new here (so if this post is in the wrong forum point me in the right direction), and fairly new to unix. I have a macbook pro and just recently started messing around with the Single User Mode, where i can manipulate directories/files/etc using unix. I have also just recently learned how to log in as an administrator using the passwd root command and such, which i thought was an interesting hole/hack in the system security and im just curious if anyone knows any other interesting commands/hacks n such that i can mess around with? Like for instance if i wanted to be a real jerk and delete someones operating system (in my case OSX) files and ruin their computer? Not that i would do such a thing, but just curious if its possible. Or any other loopholes or even beneficial mods or anything i can do while in this single user mode?