My colleague who seems to get involved in all sorts of money-related shenanigans once found himself wrapped up in a money mystery not of his own devising.
Back in the days before direct deposit, you received your pay in the form of a paper check. The group administrator would go through the halls with a handful of checks and personally hand them to each employee. (This was therefore an important reason to be nice to your group administrator.)
For some reason, my colleague didn't get a visit from the group administrator. Instead, at every pay period he got a piece of email from the Building 1 receptionist that went something like this:
Hi. For some reason, I have your paycheck. Can you come by and pick it up? Thanks.
Twice a month, my colleague would walk over to Building 1 and make some small talk with the receptionist as he picked up his paycheck.
We never did figure out why my colleague's paycheck was being sent to the wrong place. His guess was that although Microsoft knew he was an employee and had to pay him, some database glitch prevented his salary from being assigned to the appropriate organization. Faced with this conflict ("I have to pay this guy, but I don't know where to send the check"), the payroll system used a fallback rule of "When all else fails, send it to the Building 1 receptionist."
If this theory were true, then it also meant that the ledger for the Windows division was not being charged for his salary. He was instead being paid out of some mysterious pile of money in the payroll department.
My colleague was the sort of person who enjoyed these sorts of glitches and preferred not to interfere so that he could see how they manage to resolve themselves. How long would it take the payroll department to realize that the Windows division was getting a free employee?
Or maybe the Building 1 receptionist was cute.
(I don't believe I ever learned how the issue finally resolved itself. I didn't realize that there would be a quiz 20 years later.)
Related: The fictitious story of the forgotten employee. (Note that many copies of this story do not disclose that it is fictitious.) Although the story is fake, the phenomenon of ghost employees is real.