code:

// ==UserScript==
// @name           waffler
// @include        http://forums.somethingawful.com/showthread.php?*
// ==/UserScript==

(function(){
  var images = document.getElementsByTagName('img');
  for(var a=0;a<images.length;a+=1){
    var img = images[a];
    var src = img.getAttribute('src');
    if(src.match(/\.waffleimages.com\//)){
      var match = src.match(/waffleimages\.com\/([0-9a-f]{40})\/.*(jpe?g|png|gif)$/i);
      if(match){
        var hash = match[1];
        var ext = match[2];
        if(ext == 'jpeg'){
           ext = 'jpg';
        }
        var newSrc = 'http://randomwaffle.gbs.fm/images/' + hash.substr(0,2) + '/' + hash + '.' + ext;
        img.setAttribute('src', newSrc);
      }
    }
  }
})();