jQuery.duck.js

// punch
jQuery.punch = function (obj, method, fn) {

  var hasOwnMethod = obj.hasOwnProperty(method),
      original = obj[method];

  obj[method] = function () {
    Array.prototype.unshift.call(arguments, $.proxy(original, this));
    return fn.apply(this, arguments);
  };

  $.data(obj[method], '(*)<', hasOwnMethod && original);

  return obj[method];
};

// pull
jQuery.pull = function (obj, method) {

  var original = $.data(obj[method], '(*)<');

  $.removeData(obj[method], '(*)<');

  if (original) {
    obj[method] = original;
  } else {
    obj[method] = null;
    delete obj[method];
  }

  return obj[method];
};

test.jQuery.duck.js

// view results at http://furf.com/exp/duck/duck.html

(function ($) {

  function Person (name) {
    this.name = name;          
  }
  
  Person.prototype.doSomething = function () {
    console.log(this.name + ' is doing something');
  };

  var d = new Person ('dave');

  d.doSomethingElse = function () {
    console.log(this.name + ' is doing something else');
  };



  console.group('prototype');
  
  console.group('punch');
  $.punch(Person.prototype, 'doSomething', function (orig) {
    console.log('punched!');
    orig();
  });
  d.doSomething();
  console.groupEnd('punch');
  
  console.group('pull');
  $.pull(Person.prototype, 'doSomething');        
  d.doSomething();
  console.groupEnd('pull');

  console.groupEnd('prototype');



  console.group('instance');
  
  console.group('punch');
  $.punch(d, 'doSomething', function (orig) {
    console.log('punched!');
    orig();
  });
  d.doSomething();
  console.groupEnd('punch');
  
  console.group('pull');
  $.pull(d, 'doSomething');        
  d.doSomething();
  console.groupEnd('pull');

  console.groupEnd('instance');


  console.log('weird things start to happen down here...');
  console.log('look into mapping at actual prototype if !hasOwnMethod but avoid infinite recursion');

  console.group('prototype & instance');
  
  console.group('punch');
  $.punch(Person.prototype, 'doSomething', function (orig) {
    console.log('punched! (prototype)');
    orig();
  });
  d.doSomething();
  console.groupEnd('punch');
  
  console.group('punch');
  $.punch(d, 'doSomething', function (orig) {
    console.log('punched! (instance)');
    orig();
  });
  d.doSomething();
  console.groupEnd('punch');
  
  console.group('pull');
  $.pull(Person.prototype, 'doSomething');        
  d.doSomething();
  console.groupEnd('pull');
  
  console.groupEnd('prototype & instance');



})(jQuery);