They call each other pigs. Utd call them pigs because of the blue and white (butchers - pigs) and We'd call them pigs as the red and white stripes represents bacon. It's all hilarious bantz.
The pig farm at Hillsborough is an urban myth.
So there you have it.
This from a Sheffield resident who supports the pigs. The Wednesday variety.
I googled it as well and it all stacks up.