Ground Level?

I’m waiting for the elevator. How the elevator works is everytime you pass a floor, the elevator makes a beep sound. In addition, there is a screen that shows what floor you are on etc, like most elevators. So, the Elevator finally opens and as I walk in, this cleaner walks out, and he almost hits me with his vacuum. He’s like “Sorry!! Oh I thought this was ground level” I just thought this was amusing because I am on the 8th floor and there is only one floor above me! Dumb ass