Inject jQuery

(function() {
    var script = document.createElement("script");
    script.src = "https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js";
     /* If you need callback */
    script.onload = script.onreadystatechange = function(){ };
    /* end */
    document.body.appendChild( script );
})();

It is useful if you need the jQuery in any page.
Just open your console and paste this snippet.