unknown block

I have this gray block that suddenly appeared. I know it's probably a bit of code that doesn't belong. But, I can't figure it out. Anyone have an idea? This is the code I entered just before this happened:

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script> <script>function randomChar(t){var e="";"lowerLetter"==t?e="abcdefghijklmnopqrstuvwxyz0123456789":"upperLetter"==t?e="ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789":"symbol"==t&&(e=",.?/\\(^)![]{}*&^%$#'\"");var r=e.split("");return r[Math.floor(Math.random()*r.length)]}$.fn.shuffleLettersHeading=function(t){var e=$.extend({step:3,fps:20,text:""},t);return this.each(function(){var t=$(this),r="";r=e.text?e.text.split(""):t.text().split("");for(var n=[],a=[],s=0;s<r.length;s++){var i=r;" "!=i?(/[a-z]/.test(i)?n="lowerLetter":/[A-Z]/.test(i)?n="upperLetter":n="symbol",a.push(s)):n="space"}t.html(""),function s(i){var f,h=a.length,o=r.slice(0);if(!(i>h)){for(f=Math.max(i,0);f<h;f++)f<i+e.step?o[a[f]]=randomChar(n[a[f]]):o[a[f]]="";t.text(o.join("")),setTimeout(function(){s(i+1)},1e3/e.fps)}}(-e.step)})},$(function(){$("matrixText h1").shuffleLettersHeading(),$("matrixText h2").shuffleLettersHeading(),$("matrixText h3").shuffleLettersHeading()});</script>

I know that sometimes if you leave a bit of incomplete code it'll do that. I just can't find it.