Change the default printer on a target’s computer to one in a public space.
This prank works best if there is a printer that is accessed by public clients; however, if this isn’t possible, redirecting prints to other locations will still work well. In most offices everyone uses one printer all the time, even if there are multiple printer locations in the building. By changing the default printer on computers to other locations, the print jobs will be successfully delivered, thus not triggering any error messages.
Most staff members will attempt their print job several times before looking into the real cause of the error, perhaps with the belief that their print job was accidentally picked up by another. This may lead to accusations, ill feelings and lost productivity. That is, of course, the goal.
For extra points change other defaults of the printing process. Changing the standard print size, page size and/or colours can add more mystery to why the printer has a mind of its own.