Grew up in Essex in the 80s and always heard it. Went to loads of west ham games and it was rife in the ground and pre game pubs.Now maybe. But I didn't hear much outside of chelsea before the term was flagged up as a racial term a few years ago. Out of interest how do you know other fans use it?
Again in the early 2000s at uni, was a standard throw away insult i.e no foreskin etc.
Personal experience both in life and going to a few aways