So I noticed over on Princess Fluffybutt's post about her cats' poopscapades that many people were puzzled about why cats love plastic bags so much. Lots of cats lick and/or chew (and sometimes unfortunately swallow pieces of) plastic bags. Know why?
Because they're often coated in a layer of animal fat. Makes them slide nicer. It can be any of a variety of animal-derived products, but is often beef fat. They're called "slip agents", because that sounds much nicer than rendered beef tallow. In my search for a source to provide for this bit of trivia floating around in my head, I discovered an article from 2005 raising some concerns about mad cow disease, and the potential to transmit that via plastic bags.