// ==UserScript==
// @name        _Add an image to a web page
// @include     http://stackoverflow.com/*
// @require     http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js
// ==/UserScript==

$("body").append (
    '<img id="myNewImage" src="https://www.pikpng.com/pngl/m/399-3994789_mst3k-mystery-science-theater-silhouettes-clipart.png">'
);
$("#myNewImage").css ( {
    position:   "fixed",
    width:      "128px",
    height:     "128px",
    bottom:        "0",
    right:       "0"
} );