Easy, you just say your missus ran out to help, they were drunk and accosted her, then you protected your missus from the aggresive drunk people who turned their attention to you. Must remember to give them first aid and call a ambo for them as this is a real winner with the law.
Same senario can be used for graffitti painters, substitute drunk for "they were acting crazy"
The cops really dont care to much if you touch up idiots as long as you dont cause to much work for the police, because the way the law is the cops cannot touch the filth but they will generally back you if you do.