They were (are?) a group that catalogued hate speech and general shitassery on Reddit. Arguably overzealously, but pretty close to current standards. Members were perceived as the Reddit boogeyman with deep connections to the admins and unlimited leeway. Turns out they were just a decade ahead of the times in calling out rape jokes and racism.
As I recall, they were very selective in the hate speech they documented. Posts that showed hate speech coming from their favoured groups were swiftly removed.
They only documented it when it came for a non-hateful subreddit and it had lots of upvotes and it wasn't removed by moderators, except for r/teenagers.