No obvious OS but it was a talking lift
I was once stepped into a lift at BBC TV Centre Spur when it said "8th floor going up". This was worrying in two ways: I wanted to go down since I was already on the top floor, secondly that top floor was numbered 7 so the lift seemed to have been in some alternate reality. Luckily, it took me to the 3rd floor where I wanted to go. However, I was starting to worry that my life had been more blameless than I thought and that the lift had decided to take me on shortcut to heaven by crashing through the basement.