Well that's their idea of a laugh so let them be. They'll soon learn (or by the sound of things someone already did) that the tables soon turn and suddenly its them who are getting kicked to bits. The fact that they'll know why its happened and that they've been beaten at their own game will add to their self pity. IMO knowing you didn't deserve it kind of makes it feel a tad bit better than knowing you deserved a kick in the head if you know what I mean.
Re: balls If this was on the market then there is CCTV about.. get in touch with the law.. Get this little lot banged up for GBH.. then let them get a few months / years in jail where they can be abused by other dregs of society..
It was inside a club wasn't it?. Doubt there'd be any clear evidence if any. My m8's got into a ruck with the people working in the pizza shop accross the road from the centre of life and the police said the cctv wasnt clear enough. It happened right outside the takeaway too. If there was evidence they would prolly get a caution or something stupid. Defo not GBH. ABH maybe?