Why is "Pen Pineapple Apple Pen" sweeping the nation?  Well, we aren't really sure.  It became really popular in Japan and that popularity has spread to the rest of the world.  The "artist" in the video is a comedian who does comedy under the name Piko-Taro.  He also is a DJ who goes by DJ Kosaka Daimaou.  And if that isn't confusing enough, his real name is Kazuhiko Kosaka.

Basically, this is just a comedic music video that is probably meant to be pretty much nonsense.  If you want to learn more about the video (you don't really need to know anything to enjoy this video), check out Mashable's "What's the deal with that wild Pen Pineapple Apple Pen video?" blog.