Of course I've never been at a school that wasn't coed, but my class was all-male for two years, so I do have an idea. To my knowledge there were very, very few physical fights between boys at my school - and if things got so bad as that, it was a pretty good indication that things would not be fine afterwards. Boys' bullying and cutting remarks are less subtle than girls', no doubt, but still, words are their primary kind of meanness as well, in my experience, not fighting. To get physical fighting, in the vast majority of cases, you'd have to go so far as to make someone hate so strongly as to lose control and resort to force - hardly something they're likely to get over immediately afterwards.