This app was mentioned in 1 comment, with an average of 4.00 upvotes
BoilerBall Lights is an app that uses the microphone on your phone and a 3 tone beep to synchronize all mobile devices in the stands to create a choreographed light show using the rear-facing flash on your Apple/Android device.
You can download the BoilerBall Lights App via these links on mobile: App Store | Play Store
I can’t wait to see what this looks like with 14,000+ more phones.