While this pertains to elevators, mostly, I felt it deserves it's own designation. A 'Scream Test' is something that I and a few other members of the 1997 Viewmont High Technical Theatre class thought up one evening while 'putting the stage to bed' after a show.
A Bit of explanation is required.
In the auditorium of that high school, there is a balcony. We usually have/had the follow spots, trees, etc on the balcony. One evening, after said show, we (being 3 of us) were carrying some lighting instruments down from the balcony, using the schools' elevator. On the top floor we boarded, and as soon as the doors closed, one of our party started screaming. Loudly.
So, we all joined it. What else could we do?
The Elevator ride ended some 25 seconds later, being only a 1 floor journey. At the very moment the doors began to quiver in anticipation of opening, we stopped and put our game faces back on. The door then opened, and a hallway of performers and students had the most confused expressions on their faces. However, since none of them knew exactly where the screaming had come from, they weren't about to ask us it it was, indeed, us for fear of being wrong and looking like idiots if they were wrong. They just looked oddly at us to which we said "WHAT?!?"
It's an amusing sociological test to try on people, especially in malls, to see if they are confident of their senses and perceptions. For an elevator ride with just you and your party, as soon as the doors close, start to scream bloody murder. And as soon as the doors begin to open, stop and behave as if nothing is out of the ordinary. If anyone questions you as the the sounds they think they heard, just look at them confused and stroll off.