CMD B Block Userscript

// ==UserScript==
// @name         CMD B Block
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        *://*/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
    document.addEventListener('keydown', event => {
        if(event.keyCode === 66 && (event.metaKey || event.ctrlKey)) {
            event.preventDefault();
            event.stopPropagation();
        }
    })
})();