Block GIFs from auto looping on Imgur. Press B to toggle.

prevent-gif-looping.user.js

// ==UserScript==
// @id imgur.com@scriptish
// @name prevent-gif-looping
// @version 1.1
// @namespace imgur.com
// @author Vinayak
// @description Block GIFs from looping on Imgur
// @include http*://imgur.com/*
// @run-at document-end
// ==/UserScript==
function stopLooping(){
    document.getElementsByTagName("video")[0].removeAttribute("loop");
    loop=false;
}

function startLooping(){
    document.getElementsByTagName("video")[0].setAttribute("loop", "loop");
    document.getElementsByTagName("video")[0].load();
    loop=true;
}

function doc_keyUp(e) {
    // B = key code 66. Press B to toggle looping
    if (e.keyCode == 66) {
        if(loop) { stopLooping(); } else { startLooping(); }
    }
}

document.addEventListener('keyup', doc_keyUp, false);
document.getElementsByTagName("video")[0].removeAttribute("loop");
var loop=false;