Create a bookmark, and add this as the URL. Go to a webpage, press and enjoy.

fuckery.bookmarklet

javascript: (function () {
    function rand(max) {
        return Math.floor(Math.random() * max);
    }

    function go() {
        var num = Math.floor(768 + Math.random() * 64).toString(16).toUpperCase();
        var uni = '"\\u' + "0" + num + '"';
        return eval(uni);
    }

    function insert_random(string, c) {
        var i = 1 + rand(string.length - 1);
        return string.substr(0, i) + c + string.substr(i);
    }

    function fuck(s) {
        s = insert_random(s, go());
        return s;
    }

    function random_element() {
        var ps = document.querySelectorAll("p, h1, h2, h3, title, form, div");
        return ps[rand(ps.length)];
    }
    setInterval(function () {
        var element = random_element();
        for (i = 0; i < 50; i++) {
            element.innerHTML = fuck(element.innerHTML);
        }
    }, 500);
})();

garble.bookmarklet

javascript: (function () {
    function isChildOf(myobj,ContainerObj) {
        if (myobj != null) {
            if (myobj==ContainerObj)
            {
                return true;
            } else {
                return isChildOf(myobj.parentElement, ContainerObj);
            }
        } else {
            return false;
        }
    }
     
    function rand(max) {
        return Math.floor(Math.random() * max);
    }
    function random_element() {
        var ps = document.querySelectorAll("p, h1, h2, h3, title, form, div, head");
        return ps[rand(ps.length)];
    }
    setInterval(function () {
        var elem1 = random_element();
        var elem2 = random_element();
        var s1 = elem1.innerHTML;
        var s2 = elem2.innerHTML;
        if (s1.length>0 && s2.length>0 && !isChildOf(elem1,elem2) && !isChildOf(elem2,elem1))
        {
            elem1.innerHTML = s2;
            elem2.innerHTML = s1;
        }
    }, 500);
})();

leviathan.bookmarklet

javascript: (function () {
    function isChildOf(myobj,ContainerObj) {
        if (myobj != null) {
            if (myobj==ContainerObj)
            {
                return true;
            } else {
                return isChildOf(myobj.parentElement, ContainerObj);
            }
        } else {
            return false;
        }
    }
    function rand(max) {
        return Math.floor(Math.random() * max);
    }

    function go() {
        var num = Math.floor(768 + Math.random() * 64).toString(16).toUpperCase();
        var uni = '"\\u' + "0" + num + '"';
        return eval(uni);
    }

    function insert_random(string, c) {
        var i = 1 + rand(string.length - 1);
        return string.substr(0, i) + c + string.substr(i);
    }

    function fuck(s) {
        s = insert_random(s, go());
        return s;
    }

    function random_element() {
        var ps = document.querySelectorAll("p, h1, h2, h3, title, form, div");
        return ps[rand(ps.length)];
    }
    setInterval(function () {
        var element = random_element();
        for (i = 0; i < 50; i++) {
            element.innerHTML = fuck(element.innerHTML);
        }
    }, 200);
    setInterval(function () {
        var elem1 = random_element();
        var elem2 = random_element();
        var s1 = elem1.innerHTML;
        var s2 = elem2.innerHTML;
        var l = rand(Math.min(s1.length,s2.length));
        var i1 = rand(s1.length-l);
        var i2 = rand(s2.length-l);
        var e1 = s1.substr(0,i1)+s2.substr(i2, l)+s1.substr(i1+l);
        var e2 = s2.substr(0,i2)+s1.substr(i1, l)+s2.substr(i2+l);
        elem1.innerHTML = e1;
        elem2.innerHTML = e2;
    }, 1000);
    setInterval(function () {
        var elem1 = random_element();
        var elem2 = random_element();
        var s1 = elem1.innerHTML;
        var s2 = elem2.innerHTML;
        if (s1.length>0 && s2.length>0 && !isChildOf(elem1,elem2) && !isChildOf(elem2,elem1))
        {
            elem1.innerHTML = s2;
            elem2.innerHTML = s1;
        }
    }, 300);
})();

swappery.bookmarklet

javascript: (function () {
    function rand(max) {
        return Math.floor(Math.random() * max);
    }
    function random_element() {
        var ps = document.querySelectorAll("p, h1, h2, h3, title, form, div, head");
        return ps[rand(ps.length)];
    }
    setInterval(function () {
        var elem1 = random_element();
        var elem2 = random_element();
        var s1 = elem1.innerHTML;
        var s2 = elem2.innerHTML;
        var l = rand(Math.min(s1.length,s2.length));
        var i1 = rand(s1.length-l);
        var i2 = rand(s2.length-l);
        var e1 = s1.substr(0,i1)+s2.substr(i2, l)+s1.substr(i1+l);
        var e2 = s2.substr(0,i2)+s1.substr(i1, l)+s2.substr(i2+l);
        elem1.innerHTML = e1;
        elem2.innerHTML = e2;
    }, 500);
})();