Hey, Oscar the Grouch, guess what today is? Here's a clue: it's National Grouch Day. Apparently, though, the only way to celebrate this (terrible) holiday is to not celebrate at all. It's an awful day, a really huge waste of everyone's time. Vox isn't even sure why we're celebrating it. But even Oscar can't compete with these songs Vox has gathered to help you embrace the devil on your left shoulder.