True story...

Adman gets into a elevator on the 5th floor alongside a nice young lady.

Lady (working the buttons): Hi, what floor do you need?
Adman: 4th, please!

Lady pushes the 4 button, and also tries to push the 5th floor button a couple times before realizing that she's ON the 5th floor.

Lady (nervous laughter): Oh! I'm ON the 5th floor. Duh. I want 4. I was wondering why that wasn't working! (More nervous laughter).
Adman (trying to ease her embarrassment): Ha, I've done that before. (pause) Elevators are smarter than we are, sometimes.
Lady: Yeah. (pause) I wonder if it could do my work for me?
Adman: Well, if it involves carrying people from floor to floor, maybe!

Ahhh... I've still got it!