Back in the late 80's I was running tech support for a company in the UK.
The computer dept was accessed through a numerical code locking system, the number for which which was changed every month.
The day before I went on a two week holiday to bonnie Scotland, the number was changed.
When I got back, I was the poor bastard who had to get in at 6am to check the systems before they could go operational for the day.
Guess who forgot the new codes