How to turn lights Green

Looking at apartments the other night our showing agent Andre flashed his brights while we were at a stop light and the light changed. I was amazed and asked him how? His dad was a police officer in Cleveland and apparently all traffic lights have sensors so a cop is coming down with her siren and lights on will trigger the light to change green. He said some are set to react to the siren's sound, but 90% respond to light and will change if you flicker your brights. I love secret tricks like this, little codes you can learn.