So, i'm actually very familiar with Ubuntu, love it and use it all the time. I like to think of myself as Linux savey, but what I just did pretty much has proved to me otherwise.
I was messing around with Apache2, wondering why my PHP wouldn't work on my web files, and so I went into the terminal and saw that Python was conflicting or broken, so I thought "hey, let me just remove python..."
I then proceeded to type apt-get remove python, to which the terminal displayed a large list of things it would remove, and asked me to hit 'Y' if I agreed.
Thinking they were just dependencies or something, I hit Y; and moments later I discover the terminal is deleting much more than just what I wanted it to, it was deleting pretty much everything on my system.
Freaking out, I closed the terminal hoping it would stop the process, when in reality it just continued in the background, out of control.
I ended up losing everything, and I have learned that I need to
a) backup more often
b) not be so stupid with the terminal