I got a call to deal with a "haunted" laser printer once -- it wouldn't stop printing copies of a big document. Switch it off, switch it on, it would start up again. Offline, online, more copies, flush the print queue, no luck. After some questioning it turned out an EA had requested 22 copies of this document for an important meeting, accidentally typed "222" and then tried to cancel the print run when she realised her mistake.
After some digging I found a long-forgotten printer buffer wired into the muchly-renovated office cabling structure behind a cupboard. It was one of those semi-smart types, send it a document file in EPS or similar and the number of copies required and it would spew them out to the printer independently. I power cycled the dusty box to exorcise the ghostly data stream and closed the ticket by recommending the printer buffer be removed from the system (messing with cabling structures was above my pay grade at the time).