To me, this is a brilliant idea that I would implement immediately.
Before each game, a seat ticket is drawn at random and whoever has that ticket has to sing the National Anthem in front of everyone or else they have to leave the game.
This is a 10/10.
Some (most?) would forget the words. Some would totally suck. Sometimes kids would do it and it would be adorable. The amount of social-media moments you’d get from this would be astronomical.
I’m not even asking for money from this great idea, I just want to see it happen.