gistfile1.js

Template.beatles.created = function() {
  this.i_say = 'Hello';
  this.you_say = 'Good Bye'
  this.who = 'i'
}

Template.beatles.events({
  'change select': function() { this.who = $(e.target).val(); }
});

Template.beatles.lyrics = function() { return this[this.who + '_say']; }