I first found this something like a year ago, but since I was playing the Dr. Horrible soundtrack today I decided to look it up again, and it pretty much made my night.
Of course, if you're not a fan of both Dr. Horrible's Sing-a-long Blog and the Harry Potter film series, you may not appreciate it quite as much.
I'll just post the whole thing here so you don't have to click any links. I know how you folks hate clicking links. ;-)
(I've never liked this song: )
(This, on the other hand, is one of my "morning songs")