go up behind him lift he up up by his shins (keeping him standing upright in the air) and he will fall on his face... then run, now thats my style of fighting :P

be sensible, consider you're move. You could take the high road and report him or just give him a polite warning. Try to make him understand, or get the girl to talk to him with you there just in case. perhaps if he hears how its making her feel he'll understand more. violence usually leads to more violence.

I'm loving the tips wojtas... btw im british...

It all depends on the age difference (yours and his)

- If he's older then you can beat the crap out of him till he turns to mush
- If your older by less then 24 months then you can give him a bloody nose and black eye (but thats it)
- If your older by 24-48 months then only one bloody nose or one black eye
- If your older by 4+ years then call the parents, or cops, or teachers but you can't really touch him

Bear in mind if you do decide to hit him you'll probably have the police to answer to at some point and a short stint in a prison cell.
I admire Ishy's loyalty in wanting to protect his friend but do people really want him to attack this guy and end up in a cell with a criminal record?

Shank 'em, blads. Init.

If I were you, I'd just scare them off with long words. If that doesn't work, get him where it hurts: break his femur.

I suggest that you soak him in lighter fuel, throw matches at him until he burns and then castrate him with a chainsaw. After that, choke him with a plastic bag and finish him off with a baseball bat. Be sure to tape it all and give it to the parents of the guy while you laugh manically. Or, you could just kill his parents and make a chili con carne from them.

Wait... did you say that I play too much Manhunt?

Don't be seen, and don't forget to say something or he won't know why he got beaten

you could look for some hints in saw

Well this premeditated violence thing is pretty stupid. Why don't you just talk to the guy, and threaten to beat him up if he keeps the same shit up?

You may not get in trouble for beating him up, but if you do, you'll regret it forever. Besides, violence should only be used when necessary, and you clearly don't have enough justification to say that it is necessary in this case.