I created this afternoon exploration after listening to some music on my iPhone, using the lyrics feature.
I imagined a feature that lets people in the same Facetime call join a karaoke session, getting assigned different parts of the song.
The main idea would be that accessing this feature would be very easy (button on the left of the AI-supported lyric removal feature), which would send an invite message to everyone participating in the Facetime call. Once the invite would be accepted, the participants in the call would each get assigned a color (border around their camera feeds), and the lyrics they sing would get the same color. The person that has their turn to sing would get their microphone activated, while the others are muted.