I get it, but only because my mother lived near Whitechapel and told me stories from her childhood. The also had 'rat-pits" where people would take their terrier type dogs, and pay a fee to have their dogs compete in their prowess at rat-killing. I don't know much about either of those, but after living where I did in TN, I did come away knowing a LOT more than I wanted to about dog and cock fighting.
My word regarding ferrets?
Black-footed.