Posting something that is ironic to the discussion at hand, or may not even be related at all, dragging the discussion off-topic.
Irony posting does not have to be intelligent, humorous, or on-topic. It can be another way of getting up your post count like a true douche bag. Irony posting is also a way to anger people and may be considered trolling. (Especially to those with an elitist sense of humor.)
Forum poster 1: "Nyoro~n"
Forum poster 2: "What the fuck?"
Forum poster 3: "He's just irony posting. He'll probably get banned soon."