Fun one on the subway:

Make a little prompt script for your phone or computer

>welcome to Washington, D. C., Mr. Davis
>what would you like to view?
>1-traffic lights
>2-subway
>3-mainframe
3
>Subway Control
>1-emergency shutdown
>2-accelerate line
>3-shutdown line

Interact with script while on subway, watch reactions. Wearing dark glasses also helps.