We had one group project where we made game. We had like 3 developers, one guy to do some artwork and one to do most of the project management. And at that point in the project I had done most of the work so far (but not because the others didnt do anything, I just had fun coding).

One day said artwork guy managed to accidentily revert 100 of my commits without even opening a single code file. He didn't know git and issued random commands. I wouldn't know how to fuck up a repository like that even if I wanted to. Usually I am rather calm but at that point I was a little bit pissed.