What is this Video to the tune of?

There was this YouTube channel called “JibJab” they used to do “year-in-review” videos that they reviewed the past year and it was sort of in a funny manner. This is their video for 2009. My question is WHAT SONG IS THIS VIDEO TO THE TUNE OF?

[youtube=https://www.youtube.com/watch?v=eKYe1KiwywE]