High point was definitely when we found out that if you telnetted to another box you could remotely play audio clips and the operator typically had no idea what was going on. Every single device ended up with a collection of Star Wars audio clips ... :)
In SGI tech support (East team '96, Unix team '97 - my Indigo was dewi.csd.sgi.com), it was the way we copied files around (the Troops had just come out) and also had a internal tool that would pop up a window on someone else's machine to get their attention (if they weren't directly paying attention to the multicast chat program...)
That plus the lack of a default /etc/shadow, because reasons, made for fun times. ;-)