I'll bite: In my undergrad Operating Systems we used Minix and were expected to rewrite various parts of the system ourselves as our class projects. We were al

I'll bite: In my undergrad Operating Systems we used Minix and were expected to rewrite various parts of the system ourselves as our class projects. We were all given our own systems in a smallish lab used only for this class so we didn't need to save anything. About halfway through the semester one of my classmates mistyped a cd command, didn't realize it failed, and quickly did an rm -rf. This resulted in all their work for the semester being lost. Because we had all been given our own machines nothing had been saved. After this the rest of the class started backing up our work daily.