When you really want to be passive-aggressive against your needy non-computer-literate colleagues, say what you really think about your users with a custom 404 message.
Note: the above link puts some non-work safe language in nice big bold letters ala typical Microsoft 404 prompts. You’ve been warned.
This site’s 404 is far less humorous, but I get get over my passive aggression by charging a fee for my services. 🙂