Honestly, the most important part of a thread is staying on topic. Even if you're gonna type a joke, or "troll", keeping it related to the discussion is always effective and widely welcomed (I like to do this a lot).

From past experiences, arguments will happen and my advice is to just not take it too seriously. Once you get personally offended you'll look like the fool in the end. If you ignore or dismiss them, you come out on top (most of the time).