A group of scouts come out and stand in a line across the stage. One, the announcer, stands in front of them.
Announcer: "This is a test."
All: Hmmmmmmmmmmm. (Or Beeeeeeeeep)
Announcer: This has been a test of the emergency warning system. This was only a test. If there had been a real emergency, we would have said... (Scouts throw hands overheads, yell "Ahhhhhh", and run helter-skelter off stage.)