There have been a LOT of these over the many years on the FML; why not try
the FML Search Engine?  We did some ourselves to the tunes for "A Christmas
tree", "Jingle Bells", and "Deck the Halls" (Yes, Steve and I WERE the ones
who used "feces" to rhyme with "species" as in "Deck the Halls with
misplaced feces.  Fa la la... Scent marking is in our species...", but I
don't have words handy in my computer or the time to retype them, still,
the Search Engine would find them fast, I'll bet.  (Hey, notice how I
spread the blame around for my own bad taste?)
[Posted in FML issue 2481]