Hard to not mention Weird Al, but I'm sure there has to be some real gold out there that people can share.
I know the internet ran the meme to the ground, but this shit still cracks me up. There are better Lonely Island songs musically, but this is the funniest to me.
BODY COUNT - Institutionalized (Official Music Video)
The Official Music Video for the song “Institutionalized” by Body Count.Directed By: Frankie NassoEdited by: Dom Mcinerney--iTunes: http://smarturl.it/iTunes...www.youtube.com
I've always been pretty fond of Mitch Benn's stuff
Never Went Through A Smiths Phase (The Smiths)
Boy Band (Manufactured Boy Bands in general)
He had quite a good Radio 4 comedy/music series a while back - Mitch Benn's Crimes Against Music - and it's a little annoying that a few of the best songs from there don't seem to have been released in a Youtube-friendly fashion