I knew the CTO of a major telco in the early 90s who logged all the PRIVMSGs going through their network and used it to blackmail some people who weren't "out." When I found out I tried to report it, but this CTO faked some logs for their firm, making it look like I'd hacked them, and sent them to the dean of the university I was studying at to try to get me kicked out. That was a dicey moment.

On another security issue: I owned an EFnet server at the time, so I modified my HOSTS file to be able to go online as president@whitehouse.gov