Haha, right. Anyway, ignoring that, I think it might be a good idea to clear up the possibilities:
- You can replace MacOS X with FreeBSD.
- You can install it alongside OS X and chose which one of them you want to boot when you turn on the computer
- You can run an OS X program that emulates a computer (e.g. VMWare) and install FreeBSD inside that.
The first two are the "bare metal"-variants. They're faster, but also more messy if something goes wrong. The last one is easier (since you'll always have OS X running), though in some ways a bit limited.
The "bare metal" name refers to how FreeBSD runs directly on your hardware, as opposed to inside VMWare on top of OS X.
Important detail. Is this a PowerPC mini, or one of the intel ones?