When people play loud music in the Subway I do this...
When people play loud music on the phone in the Subway, I do this:
I go close to person and I play the songs that I like, usually heavy metal... Very loud. I like to place my phone very close to the person. I want to share my favorite songs too. What's wrong with that? It's an opportunity that the person can play the songs they like and I can do the same... At the same time.
It's a magical moment. They look at me and I can feel how much they love the moment. It's "kumbaya" all over the place. Pure love in the air.