Vandalism is when you try to get a thread you don’t like removed by making the discussion therein toxic enough that they remove the entire thread and silence the OP. The easiest way to do this is to start posting controversial politics in the thread.
This has actually happened to me. My OP did not technically violate the CoC, but the discussion went off the rails, although looking back on it now, given the topic of my thread, I suppose I should have expected that it might devolve into something that I never intended.