I hear what you're saying DEDSEC but in my experience it's definitely NOT just under 18s that are 1) crap and 2) annoying. Your mate saying "get a life mate" could easily be misinterpreted as insulting - which to a kid is always likely to end up in confrontation.
Also - talking sensibly to the marshals on site at the time is more likely to get a problem resolved. Leaving it until now and talking about it here will solve nothing (might make you feel better but that's about it).
Don't get me wrong, I agree with a lot of what you say but there is always two sides to these kind of experiences. I can well imagine some little kid bitching to his mates now about some grumpy old ex-squaddie that took the piss out of his Combat Machine...
