Seems like everyone has Bieber Fever, but few people who are tween girls know exactly why that is. Why is that, anyhow? Well, if you cannot knock Justin Bieber off of Twitter's trending topics, you might as well join him, right? That's what Mark Douglas and Barely Political have done in their new music video that breaks down what this Bieber Fever is all about, and of course, the 16-year-old Canadian boy's voice is provided by a lady, comedian Carolyn Castiglia. So watch this video, and then you'll know all you'll need to know about Justin Bieber: