Pigs Is Pigs!
Where do tribbles come from? Or flatcats? Or any of the other excessively multiplying animal jokes in sf and fantasy?
"Pigs Is Pigs" by Ellis Parker Butler!
Listen to the story over at Mister Ron's Basement. It's podcast #149.
(I can't tell you how relieved I am to have finally read, or heard, this sucker....)