opinion-machine-reminder.user.js

// ==UserScript==
// @name        The Opinion Machine
// @description Hide content as a reminder of the opinion machine.
// @namespace   https://gist.github.com/CairX
// @version     0.1
// @grant       none
// @include     https://www.reddit.com/*
// @include     https://news.ycombinator.com/*
// @run-at      document-end
// ==/UserScript==

const body = document.querySelector("body");
body.innerHTML = "";
body.style.background = "#000";
document.body.appendChild(message);