I should not have to really write this guide to good conduct, but as these issues constantly resurface, and often times those perpetuating them seem like perhaps they really have lost touch with what is reasonable in their endeavours rather than are simply nasty people, here it is:
Don't result to personal insults, threats or wishing misfortune on people. It is incredibly childish. I work at a primary school and this is literally the sort of behaviour I sometimes witness in the playground. If you are older than 13, you have no excuse to be acting like this, and even if you are younger than that, you should be learning to make better choices. If I expect better conduct from a child at primary school than what you are doing, you have really, really, stooped low. "You are lower than scum" is just a more elaborate way of saying "You're a poop-head" and no less childish.