Staff standby
I've been out of aviation for some years now but there certainly used to be a way of 'fooling' the QF check in computer to accept any standby passenger as if they were a confirmed passenger. Once this had been done, a boarding card would be printed even though the flight may well be oversold. I can't state this is still the case, but it certainly used to be very easy to have the computer change a standby to confirmed without the tell tale 'evidence' that could be checked out later.
Paul