I have fond memories of when we got our Amiga 2000. Must have been around 1986 or so (which would've made me 7 years old). My oldest brother spent half a day installing the OS onto the gigantic 40 MB scsi hard drive. When he was finally done, I spent about half an hour managing to bork the entire system, so he had to do a full reinstall... good times.
Still remember he told me that "it shouldn't have been possible to do that." -- by witch he meant that while it wasn't much of a surprise that'd I'd mucked up the install -- it shouldn't have been possible to do it the way I did. Still don't remember what I did, just that it involved a lot of dragging and clicking. I doubt I'd be able to do the same thing today ;-)