Reminds me of the time I naively did "net send *" to send messages to a coworker such as "What's up dog?" at a US Air Force base hospital (I was summer hire working in the warehouse). My coworker got a kick out of it, but apparently every computer in the entire hospital was on the same domain and two frantic IT NCOs came bursting into the warehouse trying to figure out who was sending the messages. Apparently the group commander's computer was getting them too...