As web crawlers and other indexes develop more powerful search routines newsgroup and discussion posts are more easily retrieved. The angry, spiteful or sarcastic post to a newsgroup or mailing list may be read by a potential or current employer or by a friend or collegue. Understand that there is virtually no privacy in cyberspace. Download and store offline any sensitive material you acquire. Whatever you are doing at anytime could be monitored by your system administrator or by others.
Most system administrators are honorable people.
But don't stake your account or your peace of mind on it. Cyberspace is reknown for the helpfulness and generosity of its inhabitants. Keep this tradition alive by helping other people less fortunate than you. Share your knowledge with others, both online, and in the computer lab itself. This is most valuable gift you can bring to the matrix.