From the Dictionary
scrumpy n :
rough cider, farmhouse cider/cyder, clear or cloudy, still or slightly lively, native to Devon and Cornwall. [Legends abound about the fermentation process (�toss in a rusty old iron bedstead to precipitate the tannins, then a dead cow to draw out the maggots�) but while it is true that an accumulation of carbon dioxide could cause a rat or Mouse scurrying across the surface of the vat to expire and fall in, brewers of old did actually hang in a piece of meat during a long cold spell to keep the yeast viable.]
Black Rat is the name of a Cider brand from Moles Brewery.
http://homepage.ntlworld.com/scrumpy/cider/his tory1.htm
Doubtful if this practise still exist given the powers of the modern day health and safety gestapo.