Thrown from a moving train?? That's horrendous. 100 fights? That's got to be a really rough area.
A 'chav' is a stereotype. It means someone who is usually dressed in a tracksuit, wearing a cap and who wears a lot of gold jewellery. They're usually foul-mouthed, extremely unintelligent and violent. They often beat people up and steal their phone/wallet/whatever they have on them and they often film it on their mobile phones. It's called 'happy slapping'. They normally hang around in groups of 10 or so, hurling abuse at anyone passing by and starting fights with people who are on their own. Basically if you hit a chav back, the whole group kick you in. I'm lucky to be stronger than my small size suggests and a fast runner, so on the only occasion where a 'chav' has grabbed me, he's been down on his arse very quickly and I've legged it before he can get up and his mates can kick the s**t out of me. This happened in the centre of Manchester. Chav concentration seems to be a lot higher in city centres :D. I live in a small village, and we don't have many. if any. There are a few groups of lads who fit the chav stereotype, but they're often quite friendly and are never looking for trouble.
For the record, I don't believe there are really 'chavs', they're just the same belligerent, violent, horrible people you can get anywhere. 'Chav' is more of a fashion thing IMO. You get arseholes wearing tracksuits and you get them wearing suits. Same as you get some really nice people wearing tracksuits and caps.