As a lover of all types of music and former disco DJ, this is the coolest thing for me. 

DJ Cumberbund took the music from Earth, Wind & Fire's "September" and laid Ozzy Osbourne's a capella "Crazy Train" vocals over it to create the mash-up to end all mash-ups. 

It's INSANE how well it works. One might say downright... wait for it... CRAZY!!!