1) Aggravation 2) Aggravation or aggression 3) Aggressive behaviour 4) Big trouble 5) Brit exasperation 6) Exasperation, to Brits 7) Greek consumed by past grief 8) Hostile behavior, to Brits 9) Intimidatory posturing 10) Irritation 11) Irritation, casually 12) Like violent moshing, slang 13) Menacing, violent behaviour 
Aggression
Aggressive.
Aggro is British (Cockney) and Australian slang for aggravation, aggressive troublemaking.
[n] - (informal British usage) aggravation or aggression
Aggressive
noun (informal British usage) aggravation or aggression; `I skipped it because it was too much aggro`
Short for aggravation, it's the sort of thing you might expect at a football match. In other words
aggressiveness, esp. that of an urban youth gang or gang member. · trouble; irritation.