I think that the AB thing started with Man Utd as ABU - Anyone but United, hence Jo's modification.
It has now evolved so that any team can get the AB hit by having their initial letter put in place:
ABA = Arsenal
ABC = Chelsea
ABS = Spurs
and so on.
Osc, UEFA have opened proceedings.
In 1980 a group of us RAF lads were camping in Savona when trouble erupted at the England v Italy game in Turin. The local Carabinieri came on the campsite and "suggested" to any English groups of singles - lads and lasses - that it might be safer to nip over the border and into France at Ventimiglia even though we had nothing to do with the football.
This crap has been going on for decades.