Just a quick warning, there is a little bit of swearing in here. Also, I don't how to get rid of the link in the top right corner of the video, but this is the only one with the song titles, so sorry :/
Axis of Awesome's 4 Chords song, which consists of every pop song from the past 40 years. It's pretty amusing. My friends did their own version at an open mic/coffee house my church held. Seriously though, this is just really funny.