This is an amusing video. Even if you don't know the original song, its still funny.

Its the song Die Schatten werden länger from Elisabeth, sung by the characters der Tod (Death) and Rudolf, only this time they're cakes... 

Thanks to the lovely fyuvish for showing me this a while ago.  Its the sort of thing I'd do when bored, but I didn't think of this.  These people are  geniuses.