title: jQuery slideDown with easing
body: <p>How can use the slideDown() function with easing?</p>
  
  <p>Maybe extend it somehow?</p>
  
  <p>I'm looking for something like this:</p>
  
  <pre><code>jQuery.fn.slideDown = function(speed, easing, callback) {
    return ...
  };
  </code></pre>
  
  <p>So i can use it slide this<br /></p>
  
  <pre><code>$('.class').slideDown('400','easeInQuad');
  </code></pre>
  
  <p>or this<br /></p>
  
  <pre><code>$('.class').slideDown('400','easeInQuad',function(){
     //callback
  });
  </code></pre>