He worked for a company that did industrial control systems and he was in the office by himself one weekend and the phone kept ringing - apparently they had strict instructions not to answer the phone but he did it anyway.
On the other end of the line was an irate operator at the Hunsterson nuclear power plant who said something like "I'm standing on top of Reactor B and all your systems have gone down and we can't see what the f*ck is going on and what are you going to do to fix it".
Apparently there was a standard support line but the operator had decided to pick on the name of the company displayed somewhere in the software and look them up in the phone book (this was about 1990) and shout at someone.
It turned out to be nothing to do with the systems this chaps employer was responsible for - they just got the call because their name was visible!