Umm, I hate to be that guy but this is just flaming or insulting. Generally roasting means that the person in question has consented and is letting people do it for entertainment, possibly putting themselves forward rather than being asked to do it. Without that this is just mindlessly hating or spewing vitriol towards people you don't like; which is all well and good, such is the way of life, but at least properly acknowledge it and label the thread as such.