Today’s “$#*! I bookmarked and forgot to post” is the YouTube Doubler, where you pick two videos that you think would work well together (or so horribly that it’d be funny) and let the magic happen.
For easy results, mute one (in the case of my example below, mute the left one of the guy dancing). If you’re really skilled, you can find two videos that you can leave the volume on for both, like you’ll see on the Doubler Homepage. (Make sure to click that link to see a crazy mouth stretchy exercise infomercial thingy). <– Great sentence. Related.