The official non-existant operating system of many an unfortunate helpdesk.
Say, for the sake of discussion, you're a poor tech support peon charged with getting the plebes (back) online. As part of your troubleshooting script, you're required to determine what operating system the customer has. Every once in a long while, the conversation will go like this:
CSR: What operating system do you have on your computer?
The Caller, without any hesitation: Windows 97.
Do you:
Sir, there never was, and never will be, a Windows 97. Did you mean Windows 98?
Probable result: one angry, insulted customer. Could you please go to the Start Menu, click on Run, type in winver, and tell me what it says when you press OK?
Probable result: Customer is, in fact, running any of Windows XP, Mac OS 8, or some obscure UNIX set up by a genius son. Such is life. Fake it.
Don't do this. Really, really don't do this.
The obvious source of this confusion, as pointed out by Roninspoon, is the similarity between Windows version numbers (95, 98, and 2000 particularly) and Office versions (specifically Office 97). If they're made by the same company and they sound sort of similar, they must be the same thing, right? Right? This is further compounded by the similarity between Microsoft (Windows) XP and Microsoft XL 97 .
Of course, the correct course of action is the second; once you know what their computer is running it's a good idea to slip that bit of information in somewhere. Educating the lusers helps both the user in question—they know a little more about their hardware—and the next technician—because he won't have to go through the same moment of cognitive dissonance. | 
