Many years ago I was in a course which had a lab. We would log onto linux machines with network based login(kerberos IIRC). Once logged in, you could also ssh into a server available to us for running codes(limited access).

One day while the lab was in session, I was just playing with stuff and tried executing a fork bomb on the server. The moment I executed the fork bomb, all the 120 machines in the lab became unresponsive, including mine. I didnt realize at that time that they were using the same server for code execution as well as auth server. No one knew what happened and the class was dismissed.