Replaces instances of "(The) Cloud" with "(My) Butt". Ported from and Inspired by panicsteve's cloud-to-butt extension for Google Chrome, and DaveRandom's ports thereof.

cloudtobutt.user.js

// ==UserScript==
// @name Cloud to Butt
// @namespace cloudtobutt
// @description Replaces instances of "(The) Cloud" with "(My) Butt". Ported from and Inspired by panicsteve's cloud-to-butt extension for Google Chrome, and DaveRandom's ports thereof.
// @include *
// @version 1.0.1
// @grant none
// @updateURL https://gist.github.com/kalmanolah/5764435/raw/cloudtobutt.user.js
// ==/UserScript==
(function() {

    function walk(node) 
    {
        // I stole this function from here:
        // http://is.gd/mwZp7E
    
        var child, next;
    
        switch ( node.nodeType )  
        {
            case 1:  // Element
            case 9:  // Document
            case 11: // Document fragment
                child = node.firstChild;
                while ( child ) 
                {
                    next = child.nextSibling;
                    walk(child);
                    child = next;
                }
                break;
    
            case 3: // Text node
                handleText(node);
                break;
        }
    }
    
    function handleText(textNode)
    {
        var v = textNode.nodeValue;
    
        v = v.replace(/\bthe cloud\b/gi, "my butt");
        v = v.replace(/\bThe Cloud\b/gi, "My Butt");
        v = v.replace(/\bThe cloud\b/gi, "My butt");
        v = v.replace(/\bthe Cloud\b/gi, "my Butt");
        v = v.replace(/\bTHE CLOUD\b/gi, "MY BUTT");

        v = v.replace(/\bcloud\b/gi, "butt");
        v = v.replace(/\bCloud\b/gi, "Butt");
        v = v.replace(/\bCLOUD\b/gi, "BUTT");
    
        textNode.nodeValue = v;
    }

    walk(document.getElementsByTagName('body')[0]);
    walk(document.getElementsByTagName('title')[0]);
}());

It i flag in the expressions makes them case-insensitive, defeating the purpose of the eight different expressions. Removing them preserves correct capitalization.