Went into a cathedral once, and they had a guy in the massive entrance bit playing the piano, he started playing the intro to Viva la Gloria. the guy playing was fairly old (late 60's) I laughed and said that's awesome, and said it was his grandsons favourite song so he learnt to play it. I said I loved Green Day, so he went on to play the guitar riffs from loads of songs in sort of a medley, was a really awesome guy.