var generator = {

  init: function() {

    var elem = document.getElementById('insult');

    var obj = this; //cache reference to the generator object (the "this" pointer will be changed within the click function

    var button = document.getElementById('generate');

    button.addEventListener('click', function() {

      elem.innerText = obj.generateInsult();

    });

  },

  generateInsult: (function() {

    var generateInsult = function() {

      return "Thou art a "+adjs1[r(adjs1)]+", "+adjs2[r(adjs2)]+", "+nouns[r(nouns)]+"!";

    };

    function r(arr) {

      return Math.floor(Math.random() * arr.length); 

    }

    var adjs1 = ["artless", "bawdy", "beslubbering"];

    var adjs2 = ["base-court", "bat-fowling", "beef-witted"];

    var nouns = ["apple-john", "baggage", "barnacle"];

    return generateInsult;

  }())

};

​

generator.init();