He turns on the siren and turns on a strobe light on his other threads.
The motion detector can turn on a coffee maker when it senses somebody coming.
Or it can unlock a door that has an electric lock.
Connect the dry contacts of the relay in series with a LED sign's power cable. You can get a 24" model cheap on Ebay! Then program the following message into the displays memory:
Don't forget to say thank you to forum members that help you!