Organised hooliganism.
Book a venue in the city where the big match is to be played.
After the match, the punters pay a nominal amount to get in.
There's an enclosed area with a mesh steel curtain separating the two groups.
Each side has a table and chairs where they can drink as much beer as they like for one hour before the match and curse and shout at the oppo until the curtain is lifted.
Depending on the size of the groups there would be an initial 20 on 20, or 50 on 50 in the case of Millwall, followed by a 10 on 10, then maybe a 5 on 5.
Each hoolie would sign a waiver and receive free medical attention at hospitals that would be paid a premium and be known as the 'Official Hoolie Hospital'.
Admission costs would have to cover short and long term disability plans.