In which we toot the horn of TubaChristmas, celebrating its 50th brassy birthday Enlarge this image toggle caption Tim Boyle/Getty Images Tim Boyle/Getty Images On the first TubaChristmas, around 300 musicians showed up at the ice skating rink at Rockefeller Plaza in New York City, bearing their giant brass instruments. Sponsor Message YouTube "We played 'Silent Night' for five straight …