What phrases invoke screen effects in the Messages app?
Apple introduced full screen animations in the messages app with the release of iOS 10. iPhone users can send other iOS users nine different animations such as balloons, confetti and fireworks through the Messages app. These animations can be individually selected and attached to any text message, or automatically triggered by typing key phrases. Apple hasn't released an official list of what phrases invoke what screen effects, but they did demo the Happy Birthday feature at WWDC 2016.