jQuery from Chrome Console

gistfile1.js

// Paste these 7 lines into Chrome JS console.

var script = document.createElement("script");
script.setAttribute("src", "http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js");
script.addEventListener('load', function() {
  var script = document.createElement("script");
  document.body.appendChild(script);
}, false);
document.body.appendChild(script);

// Now you can toy with jQuery!

$('p#whatever').val('Foobar');