gistfile1.js

Popcorn.plugin( "foo", function() {
  return {
    _setup: function( options ) {
      options.toString = function() {
        console.log( options.text )
      };
    },
    _update: function( trackEvent, options ) {
      trackEvent.text = options.text;
    }
  };
});

popcornInstance.foo( "foo123", { text: "foo" } );

var event = popcornInstance.getTrackEvent( "foo123" );

event.toString();
// logs `foo`

popcornInstance.foo( "foo123", { text: "bar" } );

event = popcornInstance.getTrackEvent( "foo123" );

event.toString();
// logs `foo`