Spam
Point Value: 1 point
Definition: "A post containing no value, including off-topic posts or posts which derail threads."
With the advent of the "+1" system a "me too"/"i agree" post with no purpose or further elaboration of it's own in a discussion thread would also be considered spam as would "reaction" images.
Additional Comment: The word "derailing" here implies a train wreck sort of situation, not necessarily that the topic of the thread changed. Minor side tangents are not a violation of this rule unless the whole thread is impacted, or a request to return to the primary topic has been made and ignored.