Find the theater people

Just as you can count the visiting Protestants in a Catholic church just by checking out who tries to go on to the "big finish" in the Lord's Prayer, you can count the theater people in your audience with this simple trick:

1. Slightly mistime the execution of a lighting cue thus:
- Penultimate line
- Go to black
- Last line
- Resume previous lighting as actors exit
- Go to black

2. Count the number of little "hmmmhs" you hear in the audience.

3. (Optional) Note the location of each "hmmmh."