I STOLED THIS CODE lul

chicken.js

/* code blatantly stolen from @asterick	*/

(function chicken() {

  function textNodesUnder(el, transform){
    var n, a = [], walk = document.createTreeWalker(el,NodeFilter.SHOW_TEXT,null,false);
    while (n=walk.nextNode()) { transform(n); }
  }

  textNodesUnder(document.body, function (el) {
    el.nodeValue = el.nodeValue.replace(/\w+/g, function (o) {
      var out = "";
      for (var i = 0; i < 7; i++) { out += ((o[i] == (o[i] || "").toUpperCase()) ? "CHICKEN" : "chicken")[i]; }
      return out;
    })
  });

})();

👍