Here's a bookmarklet that collapses(and continues to collapse) all the post-oneboxes posted by users withe a negative userid:

    javascript:(function(){window.hidePosts=function(){$("div.user-container.monologue").filter(function(){return!!this.className.match(/user--/ig)}).not(':has(div[class="annoying-collapse"])').find('.message:has(div[class="onebox ob-post"])').each(function(){$(this).find(".content").prepend('<div class="annoying-collapse"><a href="javascript:void(0)">(Show/hide)</a>  </div>');var a=$(this).find(".ob-post-title").clone().removeClass("ob-post-title").addClass("posttitle").css("display","inline");$(this).find(".annoying-collapse").append(a);$(this).find(".annoying-collapse a").click(function(){$(this).parents(".content").find("div.onebox.ob-post").toggle()});$(this).find("div.onebox.ob-post").hide()})};hidePosts();hidePosts.inter=setInterval(hidePosts,1e3)})()


![enter image description here][1]


  [1]: https://i.sstatic.net/LoFO2.png