The most amusing (after the event) version of that was the idiot who
connected the BNC on the back of a VT220 to a thinwire ethernet network.
No, it didn't do any lasting damage, but needless to say the network went
down...
Last year the University of North Carolina began giving IBM Thinkpads to all of its
students. Over half of them had to be sent back for repairs after students confused
the ethernet port with the modem and attempted to connect them to a phone line.