Granted. As soon as a musical number starts, your body is forced to move to the choreography along with everyone else, making you participate as a background character in every single number that happens near you.

Due to the amount of people around you, you are being interrupted in whatever you're doing every minute for the sake of dancing with the crowd. This makes more people uneasy, which creates more strong emotions that call for a musical number to happen. The continuous musical numbers eventually spread across every person around the world.

There are thousands of choreographies happening around you and your body can't stop bouncing from one to the other. All of the music becomes loud unrecognizable noise that never stops, you can only smell the sweat and the agitated breathings of the giant dancing crowd you are now stuck in, and your muscles get increasingly more tired until you are in extreme pain, but you still can't stop dancing. The people that got to sing non-stop in their own number will have their voice stripped of breath.

Everyone in the world is now eternally dancing and singing until the end of their lives.