hypocommenting
hypocommenting: from the Greek 'hypo-'--below; beneath; under. The act of commenting in a thread or post on a topic that is seemingly properly related to the main topic, but is not really the intent of the original poster. Usually the hypocommenting is interspersed with more regular apropos comments, otherwise, if the hypocommenting becomes the majority, it is known as thread hijacking...
I love the direction the hypocommenting has taken in this thread.