Oh, Alex... You've entered my domain. XD
A lot of the parodies I know are not exactly clean when it comes to language... but I know of a parody of "I'm on a boat" called "I'm gary oak"... Several parodies of the "bed intruder song", etc etc etc... but here are a few of the "clean" ones I know:
"Make a Man Out of You" A parody of the Mulan song by Dragonball Z characters (if you've never watched DBZ Abridged look it up. teamfourstar.com)
Metal cover of the "Bed Intruder Song"
I'll add more if I think of them. lol